Penalties and interest
IRS penalty and interest calculator
The main calculator. Late-filing, late-payment, and accuracy penalties plus daily interest, for individuals, C corporations, S corporations, and partnerships.
IRS payment plan calculator
Paying over time? See your payoff date, the total cost, and how the 0.25% plan rate and daily interest add up.
Pay now or later
See what each month of waiting adds, and compare an IRS payment plan with a credit card or a personal loan.
Estimated tax penalty calculator
Missed or short quarterly payments. See the Form 2210 penalty for each quarter, with safe harbors and the annualized method.
Late filing penalty calculator
The 5%-a-month failure-to-file penalty, the 60-day minimum, and the interest charged on top.
Tax extension penalty calculator
Filed for more time? See what paying after April costs, and what happens if you miss the October deadline.
IRS interest calculator
Daily compounding at each quarter's official rate, with interest on penalties and a quarter-by-quarter breakdown.
IRS refund interest calculator
Refund late? When the IRS takes more than 45 days, it owes you interest. See how much.
2026 quarterly estimated tax calculator
For freelancers: your 2026 tax, self-employment tax included, and the quarterly payment that keeps you penalty-free.
For businesses
S corp and partnership late filing penalty calculator
Late Form 1065 or 1120-S? The per-owner, per-month penalty ($255 in 2026), even when no tax is owed.
Late W-2 and 1099 penalty calculator
Information returns filed or sent late cost a set amount per form, depending on how late. See yours, with the annual caps.
Payroll tax deposit penalty calculator
Late payroll tax deposits cost 2% to 15% of the deposit. See your rate and the date the next one kicks in.
Tools
IRS notice lookup
Type the number on your IRS letter, like CP14 or LT11, to see what it means, your deadline, and what to do next.
Penalty removal letter builder
See if you qualify for first-time abatement, then get a ready-to-send letter asking the IRS to remove your penalties.
Put the calculator on your website
Free for accountants and bloggers: copy one snippet and the calculator runs on your page.
Want the rules behind the numbers? The guides explain each penalty in plain English, and the FAQ has short answers to the questions people ask most.