Finance Tools
Underpayment Penalty Calculator
Estimate IRS underpayment penalties based on unpaid tax amount, annual penalty rate, and number of days underpaid.
Enter values to estimate underpayment penalty.
Note: This is a simplified daily-interest estimate. Actual IRS penalties may vary by quarter, rate changes, and safe-harbor rules.
How to use this underpayment penalty calculator
- Enter the unpaid tax amount.
- Enter the annual penalty (interest) rate.
- Enter the number of days the tax was unpaid.
- Click Calculate to estimate the penalty.
Example
If $5,000 of tax was underpaid for 120 days at a 7% annual rate:
- Estimated penalty: $115.07
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