Accuracy-related penalty applies to any additional tax
2
Current IRS Rates (2026)
FTF Penalty Rate
5%
Per month, max 25% - IRC §6651(a)(1)
FTP Penalty Rate
0.5%
Per month, max 25% - IRC §6651(a)(2)
Underpayment Interest
6%
Federal short-term rate + 3% - IRC §6601
Accuracy Penalty
20%
Of underpayment - IRC §6662(a)
IRS underpayment interest rate = Federal short-term rate + 3 percentage points. Set quarterly by IRS Notice. Current rate used: 6% (Q2 2026, per Rev. Rul. 2026-5). Verify current quarter rate at IRS.gov as rates change quarterly.
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