Tax Extension Penalty Calculator 2025 β Late Filing & Payment Penalties
Calculate your IRS penalties for filing late or paying taxes late. See failure-to-file (5%/month) and failure-to-pay (0.5%/month) penalties and total interest owed.
$
Tax not yet paid by the original due date Days after April 15 (or Oct 15 with extension)
Days after April 15 when payment is made
$0
Total Penalty + Interest
$0
Failure-to-File Penalty
$0
Failure-to-Pay Penalty
$0
Interest (est. 7%/yr)
Penalty Calculation Breakdown
How to Use This Penalty Calculator
Enter the unpaid tax amount, how many days late you filed (or plan to file), how many days late you paid, and whether you filed a Form 4868 extension. An extension eliminates the failure-to-file penalty if filed by April 15, but does NOT extend the payment deadline.
The Formula
Failure-to-File: 5% Γ unpaid tax Γ months late (max 25%)
Failure-to-Pay: 0.5% Γ unpaid tax Γ months late (max 25%)
Combined: when both apply, total monthly rate = 5% (FTF reduced by FTP amount)
Interest: ~7%/year (fed rate + 3%) on unpaid tax + penalties
Minimum FTF penalty: greater of $450 or unpaid tax (if 60+ days late)
Failure-to-Pay: 0.5% Γ unpaid tax Γ months late (max 25%)
Combined: when both apply, total monthly rate = 5% (FTF reduced by FTP amount)
Interest: ~7%/year (fed rate + 3%) on unpaid tax + penalties
Minimum FTF penalty: greater of $450 or unpaid tax (if 60+ days late)
Example
$5,000 unpaid, filed and paid 45 days late (no extension):
Failure-to-file: 5% Γ $5,000 Γ 2 months = $500 (capped at 25% = max $1,250)
Failure-to-pay: 0.5% Γ $5,000 Γ 2 months = $50
Combined (month 1-2): 4.5% + 0.5% = 5% per month = $500 FTF (net)
Interest: $5,000 Γ 7% Γ 45/365 β $43
Total: ~$593 β file as soon as possible!
Failure-to-file: 5% Γ $5,000 Γ 2 months = $500 (capped at 25% = max $1,250)
Failure-to-pay: 0.5% Γ $5,000 Γ 2 months = $50
Combined (month 1-2): 4.5% + 0.5% = 5% per month = $500 FTF (net)
Interest: $5,000 Γ 7% Γ 45/365 β $43
Total: ~$593 β file as soon as possible!
Extended
How to Request a Tax Extension
Step-by-step guide to filing Form 4868 and avoiding penalties
How to Request a Tax Extension
Filing Form 4868 β Automatic Extension
Form 4868 gives you 6 additional months to file your return (to October 15). Here's how:
- Estimate your tax liability β use last year's tax as a guide
- Pay your estimated balance by April 15 β even a partial payment reduces failure-to-pay penalties
- File Form 4868 electronically (free at irs.gov/freefile), through your tax software, or mail it to the correct IRS address
- No explanation required β the extension is automatic if filed on time and you pay the estimated tax
- File your completed return by October 15
Key Deadlines in 2025
| Deadline | Date | What Happens |
|---|---|---|
| Original filing + payment deadline | April 15, 2026 | Tax returns and payments due |
| Form 4868 extension deadline | April 15, 2026 | File this to get extension to October 15 |
| Extended filing deadline | October 15, 2026 | Final deadline with extension |
| Q1 estimated tax payment | April 15, 2026 | For self-employed / investors |
| Q2 estimated tax payment | June 16, 2026 | |
| Q3 estimated tax payment | September 15, 2026 | |
| Q4 estimated tax payment | January 15, 2027 |
Penalty Abatement Options
- First-Time Penalty Abatement (FTA): Call 1-800-829-1040 if you have no penalties in the prior 3 years and have filed all required returns
- Reasonable Cause: Write a letter explaining extraordinary circumstances β serious illness, family death, natural disaster, advice from a tax professional that was wrong
- Statutory Exception: IRS errors, incorrect written advice from the IRS
- Abatement must be requested; the IRS does not automatically waive penalties
Frequently Asked Questions
What is the penalty for filing taxes late?
The failure-to-file penalty is 5% of the unpaid tax per month (or part of a month), up to a maximum of 25%. If you are more than 60 days late, there is a minimum penalty of the lesser of $450 (2025) or 100% of the unpaid tax. Note: the penalty is on UNPAID tax β if you are owed a refund, there is no failure-to-file penalty.
What is the penalty for paying taxes late?
The failure-to-pay penalty is 0.5% of unpaid tax per month (or part of a month), up to 25%. When both failure-to-file and failure-to-pay apply in the same month, the combined rate is 5% (the failure-to-file rate is reduced by the failure-to-pay rate). Interest also accrues on unpaid tax at the federal funds rate plus 3% (approximately 7-8% annually).
Does filing for a tax extension avoid penalties?
A tax extension (Form 4868) only extends the time to FILE your return β it does not extend the time to PAY your tax. You must estimate and pay any tax owed by April 15 to avoid the failure-to-pay penalty. If you pay the estimated amount by the original deadline, you get a 6-month extension to file (to October 15) without the failure-to-file penalty.
Can the IRS waive penalties?
Yes. You can request penalty abatement if you have reasonable cause (serious illness, natural disaster, death of family member, IRS error, etc.) or if you qualify for First-Time Penalty Abatement (FTA). FTA applies if you have no penalties in the prior 3 tax years and are otherwise in good standing. Call the IRS or write a penalty abatement request letter.
What if I cannot pay my taxes at all?
File on time even if you cannot pay β this avoids the larger failure-to-file penalty. Then explore options: installment agreement (pay over time), Currently Not Collectible (CNC) status, Offer in Compromise (settle for less), or hardship deferral. The failure-to-pay penalty at 0.5%/month is manageable; the failure-to-file penalty at 5%/month is 10x larger.