ERC Claim Denied: Appealing an IRS Letter 105-C, the Deadlines That Matter, and When a Refund Suit Is the Better Path

Receiving an IRS Letter 105-C after waiting months or years for an Employee Retention Credit refund changes the situation immediately. The claim is no longer merely pending. The IRS has formally disallowed it, and an ERC claim denied appeal becomes a deadline-sensitive tax controversy matter.

Two procedural tracks now matter. First, the employer can dispute the disallowance and request review by the IRS Independent Office of Appeals. Second, federal law imposes a separate limitations period for bringing a refund suit. Those clocks must not be treated as interchangeable.

Current IRS ERC guidance says taxpayers are generally asked to dispute a Letter 105-C disallowance within 30 days and may request Appeals review. The same guidance also says an Appeals request does not extend the separate two-year period for filing suit after the original claim disallowance.

That creates the central operational rule for a denied ERC claim:

Calendar the administrative response date and the judicial refund-suit deadline separately.

A business can still be communicating with the IRS or waiting for Appeals while its ability to pursue a refund in federal court is moving toward expiration. A valid written extension such as an executed Form 907 may change that deadline, but merely requesting the extension does not.

This article addresses the post-disallowance process rather than general ERC claiming. It is educational information, not individualized tax or legal advice.

What Letter 105-C and Letter 106-C Mean

A Letter 105-C ERC disallowance is a formal IRS notice that a claim for refund or credit has been denied. The IRS’s current ERC-specific page describes Letter 105-C as the taxpayer’s legal notice that the ERC claimed as a refund or reduction of tax has been disallowed.

The letter generally identifies the reason for the decision, the date of the decision, the affected tax year or period, appeal rights, and the timeframe for commencing litigation if the taxpayer wants judicial review.

Letter 106-C is used when only part of a refund or credit claim is disallowed. The distinction matters operationally because an employer receiving a partial disallowance needs to reconcile what the IRS accepted, what it denied, what amount has actually been credited or refunded, and which amount remains disputed.

Letter	General Meaning	What to Review	Immediate Deadline Issue
105-C	Claim disallowed in full	Reason, quarters, amounts, decision date, appeal instructions	Calendar administrative response and §6532 litigation period
106-C	Claim partially disallowed	Allowed amount, denied amount, affected quarters and rationale	Calendar rights concerning the disallowed portion
Either letter	Formal claim-disallowance posture	Mailing/date information and exact instructions	Do not rely only on receipt date or advisor meeting date

The IRS’s current Letter 106-C ERC guidance likewise emphasizes the separate two-year period and the availability of Form 907 in appropriate cases.

This is also different from voluntarily withdrawing a pending ERC claim. Current IRS guidance states that taxpayers receiving Letter 105-C are not eligible to use the ERC claim withdrawal program for the tax periods covered by that disallowance because the claim has already entered a different procedural posture.

For background on ERC qualification rather than the post-denial procedure, see this overview of ERC eligibility requirements.

Common Reasons an ERC Claim May Be Disallowed

The correct protest depends on the actual reason in the letter. Current IRS materials identify several recurring problem areas in ERC claims, including insufficient proof of a qualifying government order, unsupported gross-receipts calculations, wages allocated to PPP forgiveness, related-individual wages, large-employer wage errors, supply-chain theories that fail the IRS’s requirements, claims for inappropriate quarters, and claims lacking evidence that wages were actually paid.

A denial may also involve timeliness rather than substantive ERC eligibility. This became especially important after the 2025 legislation affecting late-filed third- and fourth-quarter 2021 ERC claims.

Other disputes can involve aggregation, qualified health-plan costs, computation mistakes, recovery-startup-business status, or the treatment of a particular employee or pay period.

The list is not exhaustive. The taxpayer should begin with the actual wording of Letter 105-C or 106-C rather than guessing why the IRS acted.

ERC Claim Denied: The Two Deadlines You Need to Calendar

The strongest operational safeguard in an ERC claim denied appeal is a two-clock system.

The workflow should look like this:

Letter 105-C/106-C received → capture letter and mailing information → identify the disallowance basis → record the administrative response date → independently calculate the §6532 refund-suit deadline → gather evidence → submit dispute/protest → monitor Appeals → reassess the judicial deadline periodically.

These are related deadlines, but they arise from different procedural rules.

Deadline	Trigger	Why It Matters	Does Appeals Pause It?
Administrative response/protest	Follow the specific Letter 105-C/106-C instructions; IRS ERC guidance generally asks taxpayers to dispute within 30 days	Helps get the denial reconsidered and/or moved toward Appeals promptly	Not relevant as a tolling mechanism
Refund-suit period	Statutory notice of claim disallowance under IRC §6532(a)	Controls when refund litigation must generally be commenced	No
Form 907 extended date	Valid written agreement executed by taxpayer and IRS	Replaces the otherwise applicable suit deadline to the extent stated in the agreement	Only according to the executed agreement

The Administrative Protest Window

Current IRS ERC guidance contains an important nuance.

For Letter 105-C, the IRS says it generally asks taxpayers to dispute the disallowance within 30 days to help protect the two-year timeline. The agency also says the taxpayer may request an appeal when submitting additional information and may request Appeals review at any time within two years of the disallowance letter.

Separately, the IRS’s general Appeals guidance says formal written protests generally must be sent within the time specified in the letter offering appeal rights and that this period is generally 30 days from the date of that letter.

Therefore, employers should not convert “30 days” into a universal ERC statutory deadline detached from the actual notice.

Read the letter. Record its date. Identify any specifically stated response date and method. If the letter gives 30 days from the letter date, use that instruction unless competent authority establishes otherwise.

Do not assume that the date the mailroom opened the envelope restarts the administrative clock. Likewise, do not invent a weekend or holiday extension when calculating a date unless the governing instruction or applicable federal rule supports it.

The safest operational practice is to submit well before the stated date rather than plan around the final day.

The Two-Year Refund-Suit Limitations Period

The ERC refund lawsuit two-year deadline comes from IRC §6532(a), not from the IRS’s administrative 30-day request.

Section 6532(a)(1) generally provides that a refund suit cannot be begun after two years from the date the Secretary mails by certified or registered mail a notice of disallowance of the relevant claim or portion of the claim. A taxpayer can also trigger the period by filing a written waiver of the requirement that the IRS mail a notice of disallowance.

That statutory trigger deserves careful attention.

The statute refers to mailing of the notice of disallowance, while the IRS’s ERC operational guidance tells taxpayers that they generally have two years from the date of Letter 105-C. 

The letter and IRS account records should therefore be reviewed together when establishing the litigation calendar rather than relying casually on the date someone happened to read the notice.

Current IRS Letter 105-C guidance states unequivocally that requesting an appeal does not extend the two-year period.

For the controlling statute, see IRC §6532 refund-suit limitations period.

A Hypothetical Timeline

Assume a Letter 105-C is dated March 10.

The business should not create only one calendar reminder labeled “ERC appeal due.” It should create separate entries for:

1. the response date required or requested under the letter’s administrative instructions; and
2. the independently calculated §6532 litigation deadline tied to the statutory notice of disallowance.

Suppose the employer promptly submits its ERC disallowance response and the matter is still unresolved 18 months later.

At that point, the organization should not conclude that the litigation deadline disappeared because Appeals has the file. It should determine the exact remaining §6532 time, verify whether an effective written extension already exists, and consider with qualified counsel whether continued administrative review, Form 907, or timely litigation is appropriate.

How to File an IRS Appeal of an ERC Disallowance

An IRS appeals ERC claim request should begin by addressing the basis on which the IRS disallowed the claim.

Current Letter 105-C guidance tells employers to provide an explanation and documentation addressing the initial reason for the disallowance. If timeliness is the issue, evidence might include proof establishing when the claim was mailed or submitted. If eligibility is disputed, supporting documentation should address the relevant eligibility factor for each quarter.

The IRS Independent Office of Appeals is separate from the IRS compliance functions whose determinations are being reviewed. Appeals evaluates factual and legal disputes and, where appropriate, litigation hazards.

Current IRS descriptions state that Appeals may uphold the IRS position, conclude that the taxpayer’s position is supported, or resolve a matter through compromise when facts or law create appropriate uncertainty. That should not be interpreted as a promise that any ERC appeal will settle or that every dispute can be resolved through percentage-based compromise.

What the Protest Letter Should Contain

A protest letter ERC denial should be organized as a factual and legal response, not a declaration that “we qualify for ERC.”

IRS Publication 5 says a formal written protest generally includes the taxpayer’s identifying and contact information, a statement requesting Appeals consideration, the disputed tax periods and issues, reasons for disagreement, supporting facts, supporting law or authority where applicable, and the prescribed penalties-of-perjury declaration.

The exact requirement depends on the taxpayer and the case.

Protest Section	What to Include	Supporting Evidence
Identification	Taxpayer name, EIN, contact details	Letter 105-C/106-C
Appeal request	Statement requesting Appeals review	Copy of disallowance
Periods and amounts	Each disputed quarter and amount	Form 941-X, IRS correspondence
Issue statement	IRS reason and taxpayer disagreement	Disallowance language
Facts	Quarter-specific operational and payroll facts	Orders, ledgers, payroll records
Authority	Applicable statute, notice, regulation or other authority	Citations to governing guidance
Exhibits	Indexed supporting records	Exhibit list
Declaration	Required penalties-of-perjury language when applicable	Signed protest

Publication 5 generally permits a Small Case Request if the amount for each period does not exceed $25,000, while a formal written protest is generally required if a period exceeds $25,000. Certain categories require formal protest regardless of amount. 

Employers should apply the current Publication 5 rules to their actual taxpayer type and case rather than assuming every ERC claim follows the same form.

See the current IRS protest guidance before finalizing a submission.

Where and How to Submit It

Do not send an ERC protest to a national Appeals address found in an old article or online discussion.

Current IRS Appeals guidance instructs taxpayers to send the appeal request to the IRS office identified in the letter granting appeal rights. The originating IRS function reviews the protest and, if it cannot resolve the issues, forwards the case to Appeals.

For ERC disallowances, follow the precise address, fax, upload, or other submission instructions in Letter 105-C or 106-C and any current accompanying IRS correspondence.

Preserve evidence of what was sent and when. Depending on the authorized method, that may include postal evidence, tracking information, fax transmission reports, document-upload confirmations, and a complete copy of the filed package.

Representation Before Appeals

A taxpayer may participate directly or use an authorized representative.

Current IRS Appeals guidance states that a taxpayer who wants a representative to communicate with the IRS without the taxpayer should provide Form 2848, Power of Attorney and Declaration of Representative, where applicable.

The representative should be authorized to practice before the IRS for the matter involved.

An Appeals preparation packet can include a one-page issue summary, chronology, amounts by quarter, the exact disallowance reason, the strongest exhibits, unresolved legal questions, and the taxpayer’s requested resolution.

Why an IRS Appeal Does Not Automatically Preserve Your Right to Sue

This is the most important distinction in the article.

An employer can still be discussing the ERC claim with the IRS or Appeals while the §6532 refund-suit limitations period continues running.

IRC §6532 specifically states that reconsideration of a claim after mailing of a notice of disallowance does not extend the period for bringing suit unless the taxpayer and IRS agree to an extension in writing.

The IRS reiterated this rule for ERC disputes in April 2026 when it announced its streamlined Form 907 process. The agency said taxpayers may protest an ERC disallowance through Appeals, but the administrative appeal does not extend the statutory two-year deadline.

This means “Appeals is still reviewing our case” is not itself a limitations defense.

If the period expires without timely litigation or a valid extension, the consequences can be severe. Current IRS guidance states that it cannot issue the refund or credit after the two-year period if no timely suit was filed or valid written extension was put in place, even if the administrative process later becomes favorable.

Calendar Two Deadlines, Not One

A practical statute-tracking sheet should look something like this:

Event	Date	Deadline/Status	Owner	Proof
Letter 105-C/106-C date	___	Recorded	Tax director	Notice PDF
Administrative response date	___	___	CPA/controller	Calendar
Protest submitted	___	Completed/pending	Tax owner	Mailing/upload proof
Appeals assigned	___	Pending	Representative	Appeals letter
Form 907 requested	___	Requested only	Counsel	Submission record
Form 907 executed	___	Effective through ___	Counsel	Countersigned form
Refund-suit deadline	___	___	Counsel/CFO	Statute memo

Larger organizations should also implement same-day mailroom routing for IRS correspondence. Scan both the notice and envelope, log certified or registered mail information where available, route the document to the designated tax owner, and enter deadlines immediately rather than waiting for the next advisor meeting.

Form 907 and Other Ways to Protect the Litigation Window

Form 907, Agreement to Extend the Time to Bring Suit, implements the written-extension concept authorized by §6532(a)(2).

Current IRS guidance is particularly important here because the process was expanded for ERC disallowances in 2026.

If an employer has responded to the ERC disallowance, is awaiting action, and has six months or less remaining in the two-year period, the IRS currently provides a streamlined process for requesting an extension. The employer completes and signs Form 907 and can submit it through the IRS Document Upload Tool under the CP320B selection in circumstances described by the IRS.

If an Appeals Officer has already been assigned, current IRS guidance says the taxpayer should contact that officer directly about the extension request.

Most importantly:

Submitting Form 907 is not enough.

The extension is not valid until the IRS signs the agreement and returns the countersigned form. IRS Notice CP320B guidance further states that the agreement must be signed by both parties before the existing two-year period expires.

See the official Form 907, Agreement to Extend the Time to Bring Suit.

What Form 907 Does—and Does Not Do

An executed Form 907 extends the time to bring the refund suit to the date agreed to by the taxpayer and IRS.

There is no universal extension duration that employers should insert based on an article. The actual agreed expiration date controls.

The form does not automatically establish ERC eligibility. It does not concede the refund amount. It does not force Appeals to settle the case. And an unsigned taxpayer submission does not create an extension.

Form 907 can be useful when administrative consideration remains active, the statute is approaching, and both sides are willing to preserve time for continued review without immediately moving into litigation.

It is not an automatic right.

Protective Claims Are a Different Concept

The phrase “protective claim” is often used too loosely.

A protective refund claim generally concerns preserving an administrative refund claim before the applicable refund-claim limitations period expires when entitlement depends on unresolved facts, litigation, legislation, or another contingency.

That is different from extending the §6532 period after the IRS has already disallowed a refund claim.

A business should not assume that labeling correspondence a “protective claim” extends an already-running refund-suit statute. Preservation of the post-disallowance litigation period depends on the governing statute, a valid written extension, or timely litigation.

Refund Suit Prerequisites and Federal Court Forums

IRC §7422 generally provides that a taxpayer cannot maintain a suit for recovery of an internal revenue tax or related amount until a refund or credit claim has been duly filed with the IRS.

See IRC §7422 administrative refund-claim requirement.

That requirement is one reason the factual and legal theory stated during the administrative process deserves careful attention. Refund litigation is also affected by doctrines limiting substantial departures from the grounds presented in the administrative refund claim—the so-called variance problem.

Counsel evaluating litigation should therefore compare the proposed court theories with the administrative claim, Form 941-X, protest, and supporting record.

U.S. District Court

Section 1346(a)(1) grants federal district courts jurisdiction, concurrent with the Court of Federal Claims, over qualifying civil actions seeking recovery of internal-revenue taxes and related amounts.

The Supreme Court’s Flora decisions established the general full-payment rule for tax refund litigation. Employment taxes can present divisible-tax considerations in certain circumstances, so jurisdiction and payment prerequisites should be evaluated for the particular ERC dispute rather than reduced to a universal statement that every employment-tax refund case requires the same payment pattern.

U.S. Court of Federal Claims

The U.S. Court of Federal Claims has nationwide jurisdiction over many monetary claims against the federal government, including tax claims, under statutes including the Tucker Act.

See the official U.S. Court of Federal Claims resources when evaluating this forum.

Forum selection can involve jurisdiction, venue, procedural rules, judicial experience, discovery, potential jury availability in district court, litigation economics, and the particular legal questions involved.

No forum is automatically preferable for every ERC case.

Why Tax Court Is Usually Not the Refund Forum

Tax Court is familiar to many businesses because it hears deficiency cases, but a Letter 105-C refund-claim disallowance generally places the employer in a refund-litigation posture rather than the ordinary deficiency-petition posture.

Current IRS Letter 105-C ERC guidance identifies the U.S. District Court with jurisdiction and the U.S. Court of Federal Claims as the forums for filing suit after disallowance.

That is why a business should not assume that receiving an ERC denial automatically creates a Tax Court petition deadline.

What Evidence Makes an ERC Appeal Stronger

A persuasive ERC disallowance response should answer a sequence:

IRS disallowance reason → applicable rule → quarter-specific facts → supporting exhibit → corrected amount requested.

The IRS’s current Letter 105-C instructions provide unusually detailed guidance about substantiation. They tell employers challenging a denial to explain why they are entitled to ERC, describe business operations, provide worksheets used to calculate the credit, and document at least one qualifying eligibility basis for each disputed quarter.

Issue	Stronger Records	Common Weakness
Government-order eligibility	Actual order, dates, highlighted provisions, operational mapping	Generic pandemic narrative
Gross receipts	Source ledgers, quarter comparisons, aggregation analysis	Spreadsheet with no reconciliation
Qualified wages	Employee/pay-period schedule, payroll registers, health costs	Credit total with no employee detail
PPP coordination	Forgiveness application and wage-allocation schedule	Same payroll dollars used twice
Aggregation	Ownership chart and controlled-group analysis	Each entity analyzed in isolation
Related-party wages	Ownership/family relationship review	Assuming every owner wage qualifies
Timeliness	Mailing evidence, tracking, IRS submission records	Relying solely on recollection

For additional context on documentation weaknesses that can create audit problems, see common ERC filing and audit mistakes.

Build the Evidence File Quarter by Quarter

Avoid one blended narrative covering every period.

For each quarter, create a repeatable file:

Q2 2020

• eligibility theory;
• dates of eligibility;
• gross-receipts or governmental-order analysis;
• qualified employees;
• qualified wages;
• health-plan costs;
• exclusions;
• PPP coordination;
• ERC calculation;
• supporting exhibits.

Then repeat the structure for each disputed quarter.

This makes it much easier to identify whether the IRS’s rationale is correct for one quarter but not another.

Government-Order Documentation

Government-order claims deserve special care.

Current IRS guidance says the employer should provide a copy of each government order relied upon, highlight the relevant provisions, explain how the order fully or partially suspended operations, and provide business records showing the operational impact. Recommendations, guidance, statements, or voluntary precautions are not substitutes for a qualifying order.

The evidence should connect:

specific authority → mandatory provision → effective dates → affected operation → degree of suspension → wages during the applicable period.

Useful supporting records can include board minutes, employee communications, customer notices, operating schedules, capacity records, location records, and contemporaneous correspondence.

A business should not argue that COVID-19 existed in its community and therefore the government-order test was met.

Supply-Chain Claims Require a Narrow Analysis

A supply-chain disruption by itself does not establish ERC eligibility.

Current IRS guidance describes only a narrow circumstance in which a supplier’s qualifying governmental shutdown may support the employer’s own suspension theory. 

The employer would need evidence that the supplier was affected by a qualifying government order, that the needed goods could not be obtained elsewhere, and that the problem caused a full or partial suspension of the employer’s operations.

A protest based merely on higher input costs, delays, shortages, or generalized pandemic supply problems is therefore vulnerable.

Gross Receipts and Qualified-Wage Workpapers

For gross-receipts claims, the IRS currently asks for an explanation of how the applicable decline test was satisfied, how aggregation was handled, records for all relevant quarters of the ERC year, and records for comparison-year quarters. The Letter 105-C guidance warns that summary records alone will not be accepted for this purpose.

The statutory percentages differ by ERC period, so the workpaper should apply the correct rule for the quarter involved rather than using one threshold across 2020 and 2021.

A good schedule identifies:

• comparison quarter;
• accounting source;
• entities included;
• adjustments, if any;
• gross receipts used;
• applicable calculation;
• reconciliation to books or tax records.

Qualified-wage schedules should identify the employee, pay period, quarter, wage amount, health-plan allocation if relevant, excluded amounts, and resulting credit.

PPP, Aggregation, and Related-Party Issues

PPP participation itself does not disqualify an employer from ERC, but wages reported as payroll costs to obtain PPP forgiveness cannot also be used to support ERC to the prohibited extent. Current IRS guidance recommends retaining the PPP forgiveness application, SBA documentation, and calculations separating PPP payroll costs from ERC wages.

Aggregation can affect gross receipts, employee counts, and other ERC determinations. An ownership chart should identify the entities, ownership percentages, common control, and the rule applied.

Related-party wage analysis requires equal care. Current IRS guidance says wages to related individuals are not qualified wages and notes that constructive-ownership rules can affect majority owners and spouses as well.

For a broader overview that includes PPP and ERC interaction, see ERC qualification and wage rules.

A Sample Evidence Index

This structure is illustrative, not mandatory:

Exhibit A – Letter 105-C or 106-C
Exhibit B – Protest/request for Appeals
Exhibit C – Quarter-by-quarter eligibility summary
Exhibit D – Governmental orders and operational mapping
Exhibit E – Gross-receipts schedules and source records
Exhibit F – Payroll and qualified-wage schedules
Exhibit G – PPP forgiveness and allocation records
Exhibit H – Ownership, aggregation, and related-party analysis
Exhibit I – Form 941-X and ERC computation worksheets
Exhibit J – Timeliness evidence, if disputed

Do not submit hundreds of pages without explaining why each exhibit matters.

How the 2025 ERC Law Changes Affect Denied Claims

The 2025 legislation materially changed the posture of certain late-filed 2021 ERC claims and expanded enforcement tools.

Public Law 119-21 was enacted July 4, 2025. Section 70605 contains ERC enforcement provisions. The IRS now refers to these provisions through its Working Families Tax Cuts materials and ERC compliance FAQs.

The most important post-disallowance questions concern the third and fourth quarters of 2021.

2025 Change	Affected Claims	Effective Date	Appeal Impact
Limitation on allowing/refunding certain ERC	Q3/Q4 2021 ERC claims filed after Jan. 31, 2024	July 4, 2025	Merits eligibility does not overcome statutory filing cutoff
Six-year assessment period	Certain Q3/Q4 2021 ERC amounts	Applies to assessments after July 4, 2025	Longer IRS assessment exposure may coexist with refund dispute
ERC promoter due-diligence provisions	Covered COVID-ERTC promoters/documents	Statutory effective rules vary by provision	Relevant mainly to promoter/preparer compliance, not a substitute eligibility rule
Employment-tax erroneous-refund-claim penalty changes	Claims within amended statutory scope	Applies according to statutory effective provisions	Reinforces need for substantiated claim positions

Late-Filed Q3 and Q4 2021 Claims

Section 70605(d) provides that no ERC under IRC §3134 may be allowed, and no refund relating to that credit may be made after July 4, 2025, unless the taxpayer filed the claim on or before January 31, 2024. The provision applies to the third and fourth quarters of 2021 under the legislation and IRS implementation.

The IRS says a claim is treated as filed on or before January 31, 2024, when it was properly mailed/postmarked or otherwise properly submitted to the appropriate IRS office by that date.

For a claim filed after that cutoff and not refunded or credited before enactment, proving ordinary ERC eligibility does not by itself overcome §70605(d).

However, Appeals remains available when the taxpayer contends the IRS incorrectly determined the filing date. The IRS specifically says a taxpayer receiving Letter 105-C under this rule may appeal if it believes the claim was in fact timely filed on or before January 31, 2024.

Evidence could therefore center on certified-mail records, postmarks, tracking history, proof of delivery, or other reliable submission records rather than government-order or gross-receipts eligibility.

Claims Already Paid Before July 4, 2025

The IRS’s implementation FAQ says §70605(d) generally does not apply when a Q3/Q4 2021 claim filed after January 31, 2024 had already been refunded or credited before July 4, 2025.

That does not mean such a claim is immune from other compliance activity. The IRS expressly notes that other examination or adjustment authority may still apply.

Extended Assessment Periods

The 2025 legislation also expanded the period during which the IRS can assess amounts attributable to certain third- and fourth-quarter 2021 ERC claims.

Current IRS Form 941-X instructions state that the assessment period for the third and fourth quarters of 2021 is now six years after the credit was claimed or from the relevant original-return date, whichever applicable statutory date is later.

Current IRS internal guidance describes the period as six years after the latest of the specified original-return filing/deemed-filing date or the date the credit/refund claim was made.

This extended assessment statute is not the same as the §6532 refund-suit statute.

An employer may therefore simultaneously be pursuing a denied refund while the IRS has a longer statutory period to assess an erroneous ERC or related liability.

That changes the risk analysis but does not mean the employer should abandon a valid claim. It means the entire factual and computational file should withstand scrutiny in both directions.

The 2025 Law Does Not Automatically Extend §6532

Nothing about the new Q3/Q4 claim cutoff or the extended assessment period should be treated as automatically changing a taxpayer’s Letter 105-C refund-suit deadline.

The refund-suit period must still be analyzed under §6532 and the specific claim-disallowance history unless a later statute expressly provides otherwise.

Appeal, Refund Suit, or Walk Away?

There is no responsible rule stating that every ERC denial should be appealed or every large denial should be litigated.

The right choice depends on the amount at issue, evidence quality, legal theory, procedural posture, expected professional cost, management time, remaining limitations period, and the organization’s broader tax exposure.

Factor	IRS Appeals	Refund Litigation
Cost	Generally less formal and often less costly	Usually materially more resource-intensive
Formality	Administrative proceeding	Federal litigation
Discovery	Limited administrative fact development	Formal litigation procedures may apply
Timing	Can be uncertain	Court-driven but not necessarily faster
Settlement framework	Appeals can consider litigation hazards within its authority	Resolution occurs through litigation or negotiated court settlement
Deadline concern	Does not automatically suspend §6532	Timely suit preserves judicial action
Record needed	Strong, organized substantiation	Strong and litigation-ready
Decision-maker	Independent Office of Appeals	Federal judge; district-court procedures differ from CFC
Jury	Not an Appeals concept	May be available in certain district-court refund cases; not in CFC

When Administrative Appeal Often Makes Sense

Appeals may be attractive where the dispute involves a curable misunderstanding, missing but strong documentation, a computational discrepancy, a filing-date issue supported by evidence, or a well-developed factual record that can be reviewed without immediately incurring litigation costs.

A modest claim amount may also make administrative resolution economically more sensible.

The employer should still monitor §6532 independently.

When a Refund Suit May Become More Attractive

Refund litigation may warrant serious evaluation when the claim value justifies the expense, the evidence is well developed, the dispute turns primarily on legal interpretation, Appeals has not resolved the matter as the limitations deadline approaches, or the IRS position appears unlikely to change administratively.

The purpose of filing suit should be to preserve and pursue the refund claim through a judicial remedy—not merely to “pressure” the IRS.

Counsel should review jurisdiction, claim sufficiency, statute issues, payment requirements, factual positions, and privilege before filing.

When Walking Away May Be Rational

Not every denial deserves additional spending.

A business may reasonably decide not to pursue a weak ERC claim after discovering that its government-order theory fails, records cannot substantiate gross receipts, PPP allocations materially reduce qualified wages, aggregation changes eligibility, related-party exclusions eliminate much of the credit, or the 2025 statute bars the claim.

Time and professional fees are legitimate economic considerations.

A useful framework is:

Expected practical value = disputed refund amount × probability-adjusted recovery − professional fees − internal time − appeal/litigation risk

The formula is only a decision framework. It does not supply a legally meaningful probability of success, and no recovery percentage should be invented.

New Evidence During Appeals

Ideally, the evidence package should be substantially developed before the case reaches Appeals.

Current IRS guidance says that when a taxpayer gives Appeals significant new information that the originating IRS function has not reviewed, Appeals may send or refer that information back to the original function for consideration.

That protects Appeals’ independent role rather than making it the first fact-finder for an undeveloped case.

A taxpayer should not withhold strong documentation intentionally just to “save” it for Appeals.

Where new evidence genuinely emerges later, provide it through the process directed by the Appeals Officer and expect possible originating-function review.

A Practical ERC Disallowance Response Workflow

A disciplined post-denial process can be organized into 21 steps:

1. Save Letter 105-C or 106-C and the envelope. Preserve the complete notice, mailing information, attachments, and scanned copies.
2. Identify full versus partial disallowance. For Letter 106-C, separate the allowed and denied components.
3. Record the notice and disallowance dates. Do this immediately rather than after substantive review.
4. Identify every affected quarter and denied amount. Build a quarter-by-quarter reconciliation.
5. Calendar the administrative response date. Follow the actual letter and current IRS instructions.
6. Separately calculate the §6532 refund-suit deadline. Do not copy the administrative deadline into the litigation field.
7. Identify each IRS disallowance ground. Quote or accurately summarize each reason internally.
8. Rebuild eligibility quarter by quarter. Do not rely automatically on the original promoter or preparer file.
9. Assemble government-order or gross-receipts evidence. Use the eligibility theory actually claimed.
10. Reconcile qualified wages. Tie employee-level records to Form 941-X calculations.
11. Review PPP, aggregation, and related-party issues. Correct weak assumptions before defending them.
12. Draft the protest issue by issue. Connect rule, fact, exhibit, and requested result.
13. Use the letter’s submission instructions. Do not substitute an address from another taxpayer’s notice.
14. Preserve submission evidence. Keep tracking, fax, upload, or other confirmation.
15. Track Appeals assignment. Maintain correspondence and representative authority.
16. Reassess the claim’s factual and economic strength. New analysis can change whether continued contest is sensible.
17. Determine whether the 2025 law applies. Pay particular attention to Q3/Q4 2021 filing dates.
18. Monitor the refund-suit clock independently. Administrative activity does not replace statute monitoring.
19. Address Form 907 or litigation before urgency develops. Do not assume an extension request is effective.
20. Choose whether to continue Appeals, litigate, settle where appropriate, or stop. Base the choice on evidence, law, cost, and remaining time.
21. Preserve the final file. Keep executed agreements, IRS decisions, refunds, court documents, and related tax adjustments.

Common ERC Appeal Mistakes

Mistake	Why It Creates Risk	Better Approach
Tracking only a 30-day response	§6532 may expire later while case remains unresolved	Maintain separate administrative and judicial calendars
Assuming Appeals tolls §6532	Current law and IRS guidance say it does not automatically do so	Verify remaining litigation period periodically
Generic “we qualify” protest	Does not rebut the actual denial	Respond to each IRS reason
No actual government order	Operational narrative alone may not establish eligibility	Provide order, provision, dates and impact
Gross-receipts summary does not reconcile	Reviewer cannot validate calculation	Tie schedules to source accounting records
Ignoring aggregation	Can alter receipts, employee count and eligibility	Prepare ownership/control analysis
Double-counting PPP wages	Overstates qualified wages	Reconcile forgiveness and ERC schedules
Document dump	Makes factual mapping difficult	Index and cite exhibits
Waiting until statute is almost expired to consider Form 907	IRS signature is required before expiration	Raise extension issue while sufficient time remains
Treating requested Form 907 as effective	Taxpayer signature alone does not extend deadline	Confirm IRS countersignature
Filing litigation after the statute	May eliminate the judicial remedy	Complete statute analysis early
Litigating solely because refund is large	Claim value cannot repair weak evidence or law	Apply evidence and cost-benefit review
Ignoring 2025 statutory changes	Q3/Q4 claim may face statutory filing limitation	Verify filing date and applicable provision

For additional background on documentation problems and related-party, PPP, government-order, and wage issues, this review of ERC audit risk and filing mistakes can help identify areas to rebuild before responding.

ERC Denial Appeal and Deadline Checklist

Use this checklist as an internal control rather than as individualized legal guidance:

• Save Letter 105-C or 106-C.
• Save the envelope and available mailing evidence.
• Record the notice/disallowance date.
• Identify every denied quarter.
• Identify the denied amount.
• Read the exact IRS disallowance reason.
• Record the administrative response or protest date shown by current instructions.
• Separately calculate the IRC §6532 refund-suit period.
• Confirm whether any valid written extension already exists.
• Reconstruct eligibility quarter by quarter.
• Gather actual governmental orders where relevant.
• Map each order to business operations.
• Rebuild gross-receipts workpapers.
• Reconcile gross receipts to source accounting records.
• Prepare employee-level qualified-wage schedules.
• Reconcile health-plan expenses.
• Verify PPP wage coordination.
• Review aggregation rules.
• Review related-party wages.
• Review large-employer rules where applicable.
• Draft a reason-by-reason protest.
• Include required protest information and declaration where applicable.
• Follow the actual letter’s submission instructions.
• Preserve proof of timely submission.
• Track Appeals assignment and correspondence.
• Review the July 4, 2025 statutory changes.
• For Q3/Q4 2021 claims, establish when the claim was filed.
• Track the §6532 deadline even while Appeals is active.
• Discuss Form 907 before the limitations period becomes urgent.
• Do not change the calendar until a Form 907 is actually executed.
• Evaluate litigation economics and jurisdiction with qualified counsel where appropriate.
• Preserve all final IRS and court correspondence.

Frequently Asked Questions

Conclusion

Letter 105-C should be treated as the start of a deadline-sensitive ERC dispute, not as another routine refund-status notice.

For an ERC claim denied appeal, the administrative response process and the federal refund-suit limitations period must be tracked independently. IRS Appeals can provide meaningful administrative review, but pursuing Appeals does not automatically stop the §6532 litigation clock.

Form 907 can create additional time in appropriate cases, but only through a valid written agreement with the IRS. A taxpayer should never treat a submitted or requested Form 907 as an effective extension before the IRS has properly executed it.

Substantively, the strongest ERC appeal files are built quarter by quarter. They connect the IRS’s reason for denial to the governing eligibility rule, specific business facts, qualified-wage calculations, and indexed supporting records.

Employers with third- or fourth-quarter 2021 claims must also determine whether the 2025 statutory filing limitation and expanded assessment rules apply.

Ultimately, the decision to continue through Appeals, pursue a timely refund suit, accept a negotiated resolution where available, or stop should reflect the claim amount, evidence quality, applicable law, cost, management burden, and time remaining under the controlling statute.