IRS Penalty & Interest Calculator - Failure to File & Pay

Q: What is the penalty for filing taxes one day late?

Even one day counts as a full month. 3 If you owe tax, you get hit with: 4.5% failure to file penalty 0.5% failure to pay penalty 4 That is 5% of your unpaid tax right away, plus daily interest. 4 If you owe nothing, there is no late filing penalty. 3

Q: What is the most the IRS can charge in penalties on one return?

The two late penalties together top out at 47.5% of your unpaid tax . Failure to file: 22.5% (25% cap, minus the pay penalty for the first 5 months) Failure to pay: 25% Interest has no cap. It keeps growing every day until the balance is zero. 1

Q: Is there a penalty for filing late if the IRS owes me a refund?

No. Both late penalties are a percent of unpaid tax . 3 If your tax is already paid in full through withholding, there is no penalty. 3 But there is a catch: to claim a refund of withholding or estimated tax, you must file within 3 years of the return due date. 15 After that, the money stays with the government for good. 15

Q: How long do IRS late penalties keep growing?

Each penalty stops at its own point: Failure to file: hits the 25% cap after 5 months 3 Failure to pay (0.5%): hits 25% after 50 months Failure to pay (1% after a levy notice): hits 25% after about 25 months Interest never stops until you pay the full balance. 1

Q: What is the IRS interest rate on unpaid taxes?

The rate is the federal short-term rate plus 3% for most taxpayers. 1 The IRS sets a new rate every quarter. 1 Since 2023, the rate has run between 6% and 8% a year . 1 Because it compounds daily, the real cost is a bit higher than the posted rate. 1

Q: Does the IRS apply my payment to tax, penalties, or interest first?

For most bills, the IRS applies money in this order: tax first, then penalties, then interest . 11 Paying down tax first is good for you, since penalties and interest are built on the tax balance. If you owe for more than one year, send a written note telling the IRS which year to apply the payment to. For a voluntary payment, the IRS normally follows that instruction. 12

Q: What is the penalty for not paying estimated taxes?

This is a separate charge under IRC §6654. 13 It works like interest, figured quarter by quarter at the IRS underpayment rate, on Form 2210. 13 You can avoid it if you pay in at least: 90% of this year's tax, or 100% of last year's tax ( 110% if your AGI was over $150,000) 13

Q: How long does the IRS have to collect unpaid taxes?

The IRS usually has 10 years from the date the tax is assessed. 14 This is called the collection statute expiration date. 14 The clock can pause during bankruptcy, an offer in compromise, or time spent outside the country. 14 If you never filed a return, the clock does not start until the IRS assesses the tax, for example through a substitute return. 14

IRS Penalty And Interest Calculator

Introduction

If you filed your tax return late, paid your tax late, or both, the IRS adds penalties and interest to what you owe. This IRS Penalty and Interest Calculator shows you how much that extra cost adds up to, and how much you need to pay to clear your balance.

Enter your tax year, your type of taxpayer, the tax you owe, and your key dates. The calculator works out three main charges:

Failure to File penalty: 5% of unpaid tax each month late, up to 25% (IRC §6651(a)(1))³
Failure to Pay penalty: 0.5% each month, up to 25%, with lower or higher rates in special cases (IRC §6651(a)(2))⁴
Interest: charged daily at the IRS quarterly rate on your tax plus penalties (IRC §6621)¹

You can also add payments you already made, an installment agreement, an IRS notice or levy, an audit change, and the accuracy-related penalty. The tool handles partnerships and S corporations too, which are charged a set dollar amount per partner or shareholder each month.³

The results show a quick summary, a step-by-step solution, a full line-by-line breakdown, charts, and month-by-month and quarter-by-quarter detail tables. That way you can see exactly where each dollar comes from before you write a check to the IRS.

How to use our IRS Penalty and Interest Calculator

Enter your tax year, how much tax you owe, your due dates, and any payments or IRS notices. The calculator shows your failure to file penalty, failure to pay penalty, accuracy penalty, daily interest, and your total balance due.

Tax Year: Pick the year the tax return covers. This sets the due dates and penalty amounts for that year.

Entity / Taxpayer Type: Choose who is filing, such as an individual, C-corporation, S-corporation, partnership, LLC, trust, or estate. This sets the filing deadline and the penalty rules.

Number of Partners: Shows up for partnerships and LLCs. Type how many partners are in the business. The late filing penalty is charged per partner, per month.³

Number of Shareholders: Shows up for S-corporations. Type how many shareholders there are. The late filing penalty is charged per shareholder, per month.³

Tax Owed Per Return: Enter the total tax on the return before you take out withholding, estimated payments, or credits.

Original Return Due Date: This fills in on its own. Change it if you file on a fiscal year instead of a calendar year.

Original Tax Due Date: The date the tax had to be paid. Interest and the failure to pay penalty both start here, even with an extension.²

Date Return Was Filed: Enter the date you sent in the return. Leave it blank if you still have not filed. The failure to file penalty stops on this date.

Calculate Through (Payoff Date): Enter the day you plan to pay the IRS. All penalties and interest are figured through this date.

Extension Filed: Turn this on if you filed a timely extension. It pushes back the filing deadline only, not the payment deadline.²

Penalties to Include: Check the penalties you want in the math: Failure to File, Failure to Pay, and the 20% Accuracy-Related penalty.⁵

Demand for Immediate Payment: Pick "Yes" and add the notice date if the IRS sent a notice and demand for immediate payment. The failure to pay rate is then 1% for each month that starts after that date.⁶

Notice of Intent to Levy: Pick "Yes" and add the date if you got a levy notice. If you do not pay within 10 days, the failure to pay rate goes up to 1% per month.⁴

Installment Agreement: Pick "Yes" if you had a payment plan, then add each start and end date. If you filed on time as an individual, the failure to pay rate drops to 0.25% per month during that time.⁴

Date of the First IRS Bill: Enter the date on the first IRS notice that billed you, if you have one. Interest on the failure to pay penalty, and on the per-partner or per-shareholder late filing penalty, starts on that date, and only if the bill is not paid within 21 calendar days (10 business days if the bill is $100,000 or more). If you pay in full within that window, no interest is charged for the time after the bill date.²⁴ Leave it blank if you have not been billed yet.

Audit or CP2000 Notice: Pick "Yes" if the IRS added more tax. Enter the date of the IRS bill for that tax and the amount. Use a minus sign if the change lowered your tax. Interest on the change counts from the original tax due date.²⁴ The failure to file penalty is figured on the corrected tax,²¹ and a lower tax also lowers the failure to pay penalty from the start.⁶ The failure to pay penalty on it starts only if you do not pay within 21 calendar days of the bill (10 business days if it is $100,000 or more).⁴

Payments & Credits: Add each payment with a name, date, and amount. Payments made before the due date lower the penalty base.⁶ Later payments lower the running balance from their date.

Tax Adjustments: Add any other change to the tax balance that is not a payment. Use a positive number to raise the balance or a negative number to lower it.

Calculate: Click this to see your summary, step-by-step math, charts, and full penalty and interest tables. Click Reset to clear everything and start over.

IRS Penalties and Interest: What You Need to Know

When you file a tax return late or pay your tax late, the IRS adds extra charges. These charges have two parts: penalties and interest. Penalties are set by tax law and grow by the month. Interest is charged on what you owe and grows every single day until the balance hits zero.¹

Failure to File Penalty (IRC §6651(a)(1))

This is the penalty for turning in your return late. It is 5% of your unpaid tax each month or part of a month, and it stops at 25%.³ Even one day late counts as a whole month.³ If your return is more than 60 days late, the IRS charges a minimum penalty.³ That minimum is either a set dollar amount ($525 for returns due in 2026) or 100% of the tax you owe, whichever is smaller.⁷

Failure to Pay Penalty (IRC §6651(a)(2))

This is the penalty for not paying your tax on time. It is 0.5% of your unpaid tax each month, and it also stops at 25%.⁴ The rate can change:

1% per month if you do not pay within 10 days after the IRS sends a Notice of Intent to Levy.⁴
1% per month for months that start after the IRS sends a notice and demand for immediate payment.⁶
0.25% per month while you are in an approved installment agreement (a payment plan), if you filed on time as an individual.⁴
For tax you did not report, such as tax added after an audit, the penalty starts only if you do not pay within 21 calendar days of the IRS bill (10 business days if it is $100,000 or more).⁴

When Both Penalties Hit at Once

If you file late and pay late in the same month, the IRS does not charge the full 5%.⁴ The failure to file penalty is cut by the failure to pay amount, so you are charged 4.5% plus 0.5%, or 5% total for that month.⁴

Accuracy-Related Penalty (IRC §6662)

If you left out income or claimed too much, the IRS can add 20% of the extra tax.⁵ This often follows an audit or a CP2000 notice, and it is a one-time charge, not a monthly one.

IRS Interest (IRC §6621)

Interest starts on the original tax due date, even if you got an extension to file.² The rate is the federal short-term rate plus 3%, and the IRS sets a new rate every three months.¹ Interest is compounded daily, and it is charged on your tax and on your penalties.¹ That is why a balance can grow fast if you ignore it.

Interest on the failure to file and accuracy-related penalties runs from the return due date, including extensions.² Interest on the failure to pay penalty, and on the per-partner or per-shareholder late filing penalty, starts only after the IRS bills it and the bill goes unpaid for 21 calendar days (10 business days if it is $100,000 or more).²⁴

Partnerships and S Corporations

These businesses often owe no tax themselves, so their late-filing penalty works differently. Under IRC §6698 and §6699, the IRS charges a flat amount ($255 for returns due after 2025) per partner or shareholder, per month, for up to 12 months.³ A 5-partner firm that files 4 months late can owe $5,100, with no tax due at all.

Key Due Dates

Individuals, trusts, estates, C corporations: April 15⁸²³
Partnerships, LLCs, S corporations: March 15⁸
Extensions: usually 6 more months to file, but never more time to pay⁸

How to Lower What You Owe

File your return even if you cannot pay.¹⁵ The failure to file penalty is 10 times bigger than the failure to pay penalty, so filing on time saves the most money. Pay whatever you can right away to shrink the base that penalties and interest are built on. If you filed on time, you can also ask for a payment plan to drop the pay penalty to 0.25%.⁴ You can request First-Time Abatement if you have a clean record for the past three years.⁹ Penalties can be removed for reasonable cause, but interest is almost never forgiven unless the penalty it was charged on is removed first.³

This tool gives an estimate. Your real IRS bill may differ based on how the IRS applies payments and dates. Check your IRS notice or talk to a tax pro before you send money.

Formulas used

Tax Base for Penalties and Interest

B = \max\left(T_{\text{owed}} - P_{\text{pre-due}} + A_{\text{pre-due}},\; 0\right)

Failure to File Penalty (individual/corporate, monthly, 25% cap) ³

\text{FTF} = \min\left(\sum_{m=1}^{\min(M_F,\,5)} \left(5\% \times B_F - \text{FTP}_{m}\right),\; 25\% \times B_F\right), \quad B_F = B + \text{audit change}

Minimum Failure to File Penalty (return more than 60 days late) ³

\text{FTF}_{\min} = \min\left(M_{\text{stat}},\; B\right) \quad \text{applied if } \text{FTF}_{\min} > \text{FTF}

Failure to File Penalty (Partnership \S6698 / S-Corp \S6699) ³

\text{FTF} = \min(M_F,\,12) \times p_{\text{unit}} \times N_{\text{partners/shareholders}}

Failure to Pay Penalty (monthly, 25% cap) ⁴

\text{FTP} = \min\left(\sum_{m=1}^{M_P} r_m \times B_m,\; 25\% \times B\right),\quad r_m \in \{0.25\%,\;0.5\%,\;1\%\}

Accuracy-Related Penalty (IRC \S6662) ⁵

\text{ARP} = 20\% \times U

Interest, compounded daily by quarterly IRS rate (IRC \S6621)

I = \sum_{d=1}^{D} \left(B_d + \text{Pen}_d + I_{d-1}\right) \times \frac{r_d}{365 \text{ or } 366}

Balance Due on Payoff Date

\text{Balance} = B + A_{\text{post-due}} + \left(\text{FTF} + \text{FTP} + \text{ARP}\right) + I - P_{\text{post-due}}

Frequently asked questions

What is the penalty for filing taxes one day late?

Even one day counts as a full month.³ If you owe tax, you get hit with:

4.5% failure to file penalty
0.5% failure to pay penalty⁴

That is 5% of your unpaid tax right away, plus daily interest.⁴ If you owe nothing, there is no late filing penalty.³

What is the most the IRS can charge in penalties on one return?

The two late penalties together top out at 47.5% of your unpaid tax.

Failure to file: 22.5% (25% cap, minus the pay penalty for the first 5 months)
Failure to pay: 25%

Interest has no cap. It keeps growing every day until the balance is zero.¹

Is there a penalty for filing late if the IRS owes me a refund?

No. Both late penalties are a percent of unpaid tax.³ If your tax is already paid in full through withholding, there is no penalty.³

But there is a catch: to claim a refund of withholding or estimated tax, you must file within 3 years of the return due date.¹⁵ After that, the money stays with the government for good.¹⁵

How long do IRS late penalties keep growing?

Each penalty stops at its own point:

Failure to file: hits the 25% cap after 5 months³
Failure to pay (0.5%): hits 25% after 50 months
Failure to pay (1% after a levy notice): hits 25% after about 25 months

Interest never stops until you pay the full balance.¹

What is the IRS interest rate on unpaid taxes?

The rate is the federal short-term rate plus 3% for most taxpayers.¹ The IRS sets a new rate every quarter.¹

Since 2023, the rate has run between 6% and 8% a year.¹ Because it compounds daily, the real cost is a bit higher than the posted rate.¹

Does an IRS payment plan stop interest from adding up?

No. Interest keeps running every day until the balance is paid off.²

A payment plan does help in one way: if you filed on time as an individual, it cuts the failure to pay penalty from 0.5% to 0.25% per month.⁴ A long-term plan also has a setup fee, which is lowest ($29) if you apply online and pay by direct debit.¹⁷

Does the IRS apply my payment to tax, penalties, or interest first?

For most bills, the IRS applies money in this order: tax first, then penalties, then interest.¹¹ Paying down tax first is good for you, since penalties and interest are built on the tax balance.

If you owe for more than one year, send a written note telling the IRS which year to apply the payment to. For a voluntary payment, the IRS normally follows that instruction.¹²

What is the penalty for not paying estimated taxes?

This is a separate charge under IRC §6654.¹³ It works like interest, figured quarter by quarter at the IRS underpayment rate, on Form 2210.¹³

You can avoid it if you pay in at least:

90% of this year's tax, or
100% of last year's tax (110% if your AGI was over $150,000)¹³

How long does the IRS have to collect unpaid taxes?

The IRS usually has 10 years from the date the tax is assessed.¹⁴ This is called the collection statute expiration date.¹⁴

The clock can pause during bankruptcy, an offer in compromise, or time spent outside the country.¹⁴ If you never filed a return, the clock does not start until the IRS assesses the tax, for example through a substitute return.¹⁴

What counts as reasonable cause for the IRS to remove a penalty?

Reasonable cause means something outside your control stopped you from filing or paying.¹⁰ Common examples:

Serious illness or death in your close family
Fire, flood, or a declared disaster
Records destroyed or held by someone else
Relying on a tax advisor, for an accuracy-related penalty, in some cases¹⁰

Ask by calling the number on your notice or by filing Form 843.¹⁰ Simply not having the money is usually not enough on its own.¹⁰

Does the IRS pay me interest if my refund is late?

Yes. If the IRS takes more than 45 days after the due date (or after you file, if later) to send your refund, it owes you interest at the quarterly rate.²

Watch out: that interest is taxable.¹⁸ You will get a Form 1099-INT if it is $10 or more.¹⁸

Can I deduct IRS penalties and interest on my tax return?

Penalties are not deductible. A business usually cannot deduct penalties and fines it pays to a government agency because it broke the law.²⁰

Interest paid to the IRS on your personal federal income tax is also not deductible.¹⁹ The rule that bars deducting personal interest, including interest on underpayments of individual income taxes, applies only to taxpayers other than a corporation.²⁵ Interest charged on employment taxes assessed on a business is deductible.²⁶

How much do I have to pay by April 15 to avoid the late payment penalty?

If you file an extension, pay at least 90% of your total tax by the original due date.²¹ If the part left unpaid is no more than 10% of the tax and you pay it with your return, the IRS treats the late payment as having reasonable cause, so no failure to pay penalty applies for the extension period.²¹

Interest still applies to any unpaid amount from the original due date forward.² An extension gives you more time to file, never more time to pay.²

What happens if I have not filed taxes in several years?

The IRS usually wants the last six years of returns to treat you as caught up.¹⁶ If you never file, the IRS can build a substitute return for you using only the income it sees, which may not give you credit for deductions, and then bill you.¹⁵

File the oldest years first. Penalties and interest stop growing on each year once it is filed and paid.

What is a CP2000 notice and does it mean I owe a penalty?

A CP2000 is not a bill.²² It says the income on your return does not match what employers, banks, or brokers reported to the IRS, and it proposes changes to your tax.²²

Reply by the date listed on the notice to agree or dispute it.²² If extra tax stands, interest runs until it is paid and penalties may apply.²² In bigger cases that can include a 20% accuracy-related penalty under IRC §6662.⁵

Sources

Quarterly interest rates. Internal Revenue Service. Accessed September 26, 2026.

Interest. Internal Revenue Service. Accessed September 26, 2026.

Failure to file penalty. Internal Revenue Service. Accessed September 26, 2026.

Failure to pay penalty. Internal Revenue Service. Accessed September 26, 2026.

Accuracy-related penalty. Internal Revenue Service. Accessed September 26, 2026.

26 U.S. Code § 6651 - Failure to file tax return or to pay tax. Legal Information Institute, Cornell Law School. (b), (d). Accessed September 26, 2026.

Revenue Procedure 2024-40. Internal Revenue Service. Section 2.53. Accessed September 26, 2026.

Publication 509 (2026), Tax Calendars. Internal Revenue Service. Fiscal-Year Taxpayers. Accessed September 26, 2026.

Administrative penalty relief. Internal Revenue Service. Accessed September 26, 2026.

Penalty relief for reasonable cause. Internal Revenue Service. Accessed September 26, 2026.

Topic no. 653, IRS notices and bills, penalties and interest charges. Internal Revenue Service. Accessed September 26, 2026.

Internal Revenue Manual 5.1.2, Remittances, Form 809 and Designated Payments. Internal Revenue Service. 5.1.2.9. Accessed September 26, 2026.

Underpayment of estimated tax by individuals penalty. Internal Revenue Service. Accessed September 26, 2026.

Time IRS can collect tax. Internal Revenue Service. Accessed September 26, 2026.

Filing past due tax returns. Internal Revenue Service. Accessed September 26, 2026.

Internal Revenue Manual 5.1.11, Delinquent Return Investigations. Internal Revenue Service. 5.1.11.7.1. Accessed September 26, 2026.

Payment plans installment agreements. Internal Revenue Service. Accessed September 26, 2026.

Topic no. 403, Interest received. Internal Revenue Service. Accessed September 26, 2026.

Interest, investment, money transactions. Internal Revenue Service. Accessed September 26, 2026.

Publication 334 (2025), Tax Guide for Small Business. Internal Revenue Service. Expenses You Cannot Deduct. Accessed September 26, 2026.

26 CFR 301.6651-1, Failure to file tax return or to pay tax. Electronic Code of Federal Regulations. (c)(3). Accessed September 26, 2026.

Understanding your CP2000 series notice. Internal Revenue Service. Accessed September 26, 2026.

Instructions for Form 1041 and Schedules A, B, G, J, and K-1. Internal Revenue Service. When To File. Accessed September 26, 2026.

26 U.S. Code § 6601 - Interest on underpayment, nonpayment, or extensions of time for payment, of tax. Legal Information Institute, Cornell Law School. (a), (e)(2)-(3). Accessed October 7, 2026.

26 CFR 1.163-9T, Personal interest (temporary). U.S. Department of the Treasury. paras. (a) and (b)(2)(i)(A). Accessed October 7, 2026.

Publication 535 (2022), Business Expenses. Internal Revenue Service. ch. 4, Interest You Can Deduct. Accessed October 7, 2026.

IRS Penalty And Interest Calculator

Tax Return Information

Penalties to Include

IRS Notices & Special Conditions

Installment Agreement Periods

Payments, Credits & Adjustments

Payments & Credits

Tax Adjustments (non-payment balance changes)

Rate this calculator

Introduction

How to use our IRS Penalty and Interest Calculator

IRS Penalties and Interest: What You Need to Know

Failure to File Penalty (IRC §6651(a)(1))

Failure to Pay Penalty (IRC §6651(a)(2))

When Both Penalties Hit at Once

Accuracy-Related Penalty (IRC §6662)

IRS Interest (IRC §6621)

Partnerships and S Corporations

Key Due Dates

How to Lower What You Owe

Formulas used

Frequently asked questions

What is the penalty for filing taxes one day late?

What is the most the IRS can charge in penalties on one return?

Is there a penalty for filing late if the IRS owes me a refund?

How long do IRS late penalties keep growing?

What is the IRS interest rate on unpaid taxes?

Does an IRS payment plan stop interest from adding up?

Does the IRS apply my payment to tax, penalties, or interest first?

What is the penalty for not paying estimated taxes?

How long does the IRS have to collect unpaid taxes?

What counts as reasonable cause for the IRS to remove a penalty?

Does the IRS pay me interest if my refund is late?

Can I deduct IRS penalties and interest on my tax return?

How much do I have to pay by April 15 to avoid the late payment penalty?

What happens if I have not filed taxes in several years?

What is a CP2000 notice and does it mean I owe a penalty?

Sources

IRS Penalty And Interest Calculator

Tax Return Information

Penalties to Include

IRS Notices & Special Conditions

Installment Agreement Periods

Payments, Credits & Adjustments

Payments & Credits

Tax Adjustments (non-payment balance changes)

Rate this calculator

Introduction

How to use our IRS Penalty and Interest Calculator

IRS Penalties and Interest: What You Need to Know

Failure to File Penalty (IRC §6651(a)(1))

Failure to Pay Penalty (IRC §6651(a)(2))

When Both Penalties Hit at Once

Accuracy-Related Penalty (IRC §6662)

IRS Interest (IRC §6621)

Partnerships and S Corporations

Key Due Dates

How to Lower What You Owe

Formulas used

Frequently asked questions

What is the penalty for filing taxes one day late?

What is the most the IRS can charge in penalties on one return?

Is there a penalty for filing late if the IRS owes me a refund?

How long do IRS late penalties keep growing?

What is the IRS interest rate on unpaid taxes?

Does an IRS payment plan stop interest from adding up?

Does the IRS apply my payment to tax, penalties, or interest first?

What is the penalty for not paying estimated taxes?

How long does the IRS have to collect unpaid taxes?

What counts as reasonable cause for the IRS to remove a penalty?

Does the IRS pay me interest if my refund is late?

Can I deduct IRS penalties and interest on my tax return?

How much do I have to pay by April 15 to avoid the late payment penalty?

What happens if I have not filed taxes in several years?

What is a CP2000 notice and does it mean I owe a penalty?

Sources

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