Estimated tax calculator Pay enough, on time.
Estimate the quarterly payments that may help you avoid underpayment penalties, using the federal and California safe harbor rules.
How this estimate works
Federal safe harbor: you generally avoid an underpayment penalty when withholding and timely estimates cover the smaller of 90% of this year's tax or 100% of last year's tax. The prior-year figure rises to 110% when last year's AGI was over $150,000 ($75,000 if married filing separately).
California uses its own schedule: 30% of the annual amount by the April date, 40% by June, nothing in September, and 30% in January. The 110% prior-year rule applies above the same AGI thresholds. If this year's California AGI is $1,000,000 or more ($500,000 if filing separately), the prior-year safe harbor is not available, so payments are based on 90% of this year's tax.
Withholding counts as paid evenly through the year, so the calculator subtracts expected withholding from the required annual amount before splitting it into installments.
Assumptions and limits
- Federal: no underpayment penalty applies when you owe less than $1,000 after withholding and credits.
- Farmers and fishermen have different rules, including two-thirds of current-year tax and a single January payment.
- Uses the regular installment method. The annualized income method may lower early payments when income arrives unevenly.
- 2027 due dates are computed from the statutory rules and the holiday calendar, because the 2027 IRS and FTB forms are not yet published.
- Thresholds verified October 29, 2026 against IRS and FTB guidance.
An estimate is a starting point
Income uneven, a big sale coming, or a new business this year? Planning with real numbers beats a formula. This calculator is educational and is not tax advice.
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