§ IRS Tax Topics

IRC §6654 · 26 U.S.C. §6654

IRC §6654: Failure to Pay Estimated Tax

By Paul D. Diaz, EA, MBA · Updated

IRC §6654 penalizes underpayment of estimated tax — the pay-as-you-go enforcement behind quarterly estimates. Three safe harbors avoid it: 90% of current year, 100% of prior year (110% at higher incomes), or owing under $1,000 after withholding.

What it governs

In the GuideFull treatment in Chapter 6 of the Guide — THE TAX CUTTERY® Guide to Federal Income Taxation, Professional Edition (564 pages, 24 chapters).
From the practiceDodging the underpayment penalty →

Questions this section answers

Does withholding really count as paid evenly?
Yes — whenever taken during the year. A December withholding bump can cure underpaid early quarters.
What if my income is seasonal?
The annualized-income method matches payments to when income actually arrived — built for lumpy earners.
What's the easiest safe harbor?
Prior-year tax: 100%, or 110% over $150,000 AGI. A known number, no forecasting, penalty-proof if paid evenly.
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