1. How Much Is the IRS Late Filing Penalty in 2026?
For Form 1040 and most Form 1120 returns, the IRS late filing penalty is generally 5% of unpaid tax for each month or partial month the return remains late, up to 25%. The governing rule appears in Internal Revenue Code § 6651.
The 5% Monthly Rule and the $525 Minimum
The IRS calculates the percentage-based penalty using tax required to be shown on the return, reduced by timely payments and applicable refundable credits. If the failure-to-file and failure-to-pay penalties apply during the same month, the filing penalty is generally reduced to 4.5% while the 0.5% failure-to-pay penalty applies separately. The combined charge for that overlapping month is generally 5%.
For Forms 1040 and 1120 with a return due date, without regard to an extension, after December 31, 2025, the IRS lists $525 as the applicable minimum amount when the return is more than 60 days late. The minimum is the lesser of $525 or 100% of the underpayment. The 60-day period itself is measured using the applicable filing deadline, including a valid extension. The IRS Failure to File Penalty guidance provides the current amounts and calculation rules.
| Penalty or Return Type | 2026 Rule | Maximum or Minimum |
|---|---|---|
| Form 1040 and most Form 1120 failure to file | Generally 5% of unpaid tax per month or partial month | Generally 25%; if more than 60 days late, the minimum can be the lesser of $525 or 100% of the underpayment |
| Failure to pay | Generally 0.5% of unpaid tax per month or partial month | 25% |
| Form 1065 partnership return | $255 per partner for each month or partial month late | Up to 12 months for returns with a due date, without extension, after December 31, 2025 |
| Form 1120-S S corporation return | $255 per shareholder for each month or partial month late | Up to 12 months; additional percentage-based penalties can apply when tax is due |
Form 1040 and most Form 1120 failure to file
- 2026 RuleGenerally 5% of unpaid tax per month or partial month
- Maximum or MinimumGenerally 25%; if more than 60 days late, the minimum can be the lesser of $525 or 100% of the underpayment
Failure to pay
- 2026 RuleGenerally 0.5% of unpaid tax per month or partial month
- Maximum or Minimum25%
Form 1065 partnership return
- 2026 Rule$255 per partner for each month or partial month late
- Maximum or MinimumUp to 12 months for returns with a due date, without extension, after December 31, 2025
Form 1120-S S corporation return
- 2026 Rule$255 per shareholder for each month or partial month late
- Maximum or MinimumUp to 12 months; additional percentage-based penalties can apply when tax is due
Partnership and S Corporation Returns Use Different Calculations
The 5% unpaid-tax formula should not be applied automatically to every late federal return. For Form 1065, the 2026 base penalty is generally $255 multiplied by the number of partners and each month or partial month of delinquency, for up to 12 months.
Form 1120-S uses a shareholder-based calculation for late filing. If the S corporation also owes tax, the IRS instructions provide that the shareholder-based amount can be accompanied by an additional penalty equal to 5% of unpaid tax for each month or partial month late, generally up to 25% of the unpaid tax. The IRS Form 1120-S instructions explain the applicable calculation.
These distinctions matter when reviewing an IRS notice. The return type, tax period, filing deadline, and statutory basis for the assessment should be identified before determining whether the amount is correct.
2. How AEP, FTA, and Reasonable Cause Affect Penalty Relief
Penalty relief does not depend on one universal standard. The available route can depend on the tax period, processing date, compliance history, return type, and reason for the late filing.
Automatic Exemption from Penalty and the FTA Transition
The IRS introduced Automatic Exemption from Penalty, or AEP, in summer 2026. AEP is an IRS administrative relief program and does not eliminate the underlying penalties established by federal tax law. When an eligible original return is processed, AEP can prevent certain failure-to-file, failure-to-pay, or failure-to-deposit penalties from being assessed without a separate application.
Eligibility generally requires timely filing and payment compliance during the applicable prior three-year period, or 12 consecutive quarters for quarterly filers. The IRS also applies return-specific eligibility requirements, and not every return or penalty qualifies. The current IRS administrative penalty relief guidance explains the program requirements.
First Time Abate, or FTA, remains available for specified periods during the transition. IRS guidance states that FTA continues to apply to eligible 2024 tax-year returns, eligible 2025 quarterly returns, and certain 2025 tax-year and 2026 quarterly returns processed before AEP began. For original returns with due dates of January 1, 2027, or later, FTA will no longer be available and AEP will replace it for qualifying returns.
Reasonable Cause Is a Separate Basis for Relief
A taxpayer who does not qualify for AEP or applicable FTA relief may still request abatement based on reasonable cause. For a § 6651 failure-to-file penalty, the statutory standard asks whether the failure resulted from reasonable cause rather than willful neglect. IRS guidance focuses on whether the taxpayer exercised ordinary business care and prudence but was nevertheless unable to comply on time.
Evidence can include medical records, disaster documentation, records showing an inability to obtain necessary tax information, proof of filing-system problems, or a dated chronology showing what prevented timely filing and what the taxpayer did after the obstacle ended.
Reliance on a tax professional generally does not excuse missing a known filing deadline. The IRS states that taxpayers ordinarily remain responsible for timely filing even when another person handles the return. Lack of funds, standing alone, also generally does not establish reasonable cause for failure to pay. The IRS reasonable-cause guidance explains the facts and circumstances the agency considers.
3. What Should Be Reviewed after an IRS Penalty Notice?
An IRS penalty notice should be compared with the underlying filing, extension, payment, and account records before deciding whether to request relief. The key issues are whether the IRS used the correct return type, filing deadline, filing date, unpaid-tax amount, and penalty provision.
Documents That Can Change the Analysis
Relevant records may include:
- The IRS penalty notice or letter;
- The filed return and relevant schedules;
- Electronic filing acceptance records;
- Certified-mail or approved private-delivery records;
- Form 4868 or Form 7004 extension records;
- IRS account transcripts;
- Withholding and estimated-tax payment records;
- Proof of payments or credits; and
- Contemporaneous records supporting reasonable cause.
These records address different parts of the analysis. Filing records can establish whether a return was actually late. Extension records can change the applicable filing deadline. Account transcripts and payment records can reveal whether the IRS applied payments or credits correctly. Contemporaneous documents can support the factual basis for a reasonable-cause request.
Abatement Requests and Appeals
The appropriate response depends on the notice and the reason the assessment is disputed. Some penalties can be reconsidered by contacting the IRS using the instructions on the notice. More fact-intensive matters may require a written explanation and supporting documentation.
Form 843, Claim for Refund and Request for Abatement can be used for certain requests to abate or refund penalties or additions to tax, including qualifying requests based on reasonable cause. It is not the correct procedure for every tax dispute, so the relevant notice and form instructions should be reviewed before filing.
If the IRS denies a penalty-abatement request, the taxpayer may have a right to seek review by the IRS Independent Office of Appeals. The applicable deadline and required procedure should be determined from the IRS denial letter and related appeal instructions.
4. Practical Pitfalls and Legal Review in Late-Filing Cases
Late-filing matters involve separate filing, payment, penalty, and relief rules. Treating them as a single issue can lead to an incorrect assessment of both liability and available options.
Practical Pitfalls
Waiting to file until the full tax can be paid. Filing and payment are separate obligations. Delaying a required return because the taxpayer cannot pay the full balance can allow the failure-to-file penalty to continue accruing.
Assuming a filing extension also extends the payment deadline. A valid extension generally extends the time to file, not the time to pay income tax. Interest and a failure-to-pay penalty can therefore arise even when the return is filed within an extended filing period.
Assuming an installment agreement always reduces the failure-to-pay rate to 0.25%. For an individual, the reduced failure-to-pay rate during an installment agreement generally requires that the return was filed on time, taking valid extensions into account. A late filer should not assume the reduced rate applies.
Assuming AEP erases an existing tax balance. AEP addresses specified penalties. It does not eliminate unpaid tax, interest on the underlying tax, or penalties outside the program.
What Counsel Can Evaluate and Address
Legal review can begin by reconciling the IRS notice against account transcripts, filing records, extension records, payment credits, and the applicable penalty provision. That work can identify whether the IRS used the correct statutory rule, return classification, filing date, and penalty base.
Counsel can also evaluate AEP or transitional FTA eligibility, organize reasonable-cause evidence, prepare an abatement submission, and communicate with the IRS under an authorized power of attorney. If relief is denied and appeal rights are available, counsel can identify the disputed factual and legal issues, prepare the required protest or submission, and present the taxpayer's position through the applicable Appeals process.
Where an unpaid tax balance remains, penalty relief and collection options should be analyzed separately. A payment arrangement addresses collection of the liability; it does not by itself establish that the underlying penalty assessment was correct.
5. Frequently Asked Questions
Failure-to-file questions often turn on details that are easy to overlook, including whether an extension was valid, whether any tax remained unpaid, which return was filed late, and whether administrative relief applies. The following questions address several issues that commonly affect the amount of an IRS late filing penalty or the available response.
For Form 1040 and many Form 1120 returns subject to § 6651(a)(1), the percentage-based penalty uses unpaid tax after applicable timely payments and credits. If that amount is zero, the percentage-based penalty can also be zero. Other returns, including partnership and S corporation returns, use different penalty structures.
A valid extension generally moves the filing deadline used to determine whether the return is late. It ordinarily does not extend the payment deadline, so interest or a failure-to-pay penalty can still apply to an unpaid balance.
The IRS instructs taxpayers who receive an assessed penalty but believe they qualified for AEP to contact the agency. Eligibility should be checked against the return type, processing history, prior compliance period, and other applicable program requirements.
When the IRS reduces or removes a penalty, it generally reduces or removes interest attributable to that penalty. Interest on the underlying unpaid tax is separate and is not automatically eliminated because penalty relief was granted.
16 Sep, 2026
