Safe Harbor Calculator

Enter your total tax from last year's Form 1040 (line 24) and find out exactly how much to pay each quarter to avoid IRS underpayment penalties.

Prior-year total tax (Form 1040, line 24)

My prior-year AGI was over $150,000

If yes, the safe harbor rule requires 110% instead of 100% of your prior-year tax.

Safe harbor reference tableThe safe harbor rule: pay at least 100% of prior-year tax (110% if AGI exceeded $150,000), divided into four quarterly payments.

Prior-Year Tax

Quarterly (100%)

Quarterly (110%)

$5,000

$1,250

$1,375

$10,000

$2,500

$2,750

$15,000

$3,750

$4,125

$20,000

$5,000

$5,500

$25,000

$6,250

$6,875

$30,000

$7,500

$8,250

$40,000

$10,000

$11,000

$50,000

$12,500

$13,750

How safe harbor works

Formula: safe harbor = prior-year Form 1040 line 24 total tax, ×1.10 if prior-year AGI > $150,000, divided by 4.

If you pay at least this amount each quarter, you are protected from underpayment penalties regardless of how much you actually owe. This is the simplest way to stay compliant — one number, no income projections needed.

Source: IRS Form 2210 instructions, safe harbor exception. See all due dates →

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How safe harbor works