Quarterly Estimated Tax Calculator

Figure out how much you should pay the IRS each quarter as a self-employed filer.

Methodology

Uses IRS safe-harbor rules: pay the lesser of 90% of this year's estimated tax, or 100% (110% if prior-year AGI exceeded $150,000) of last year's tax liability. Due dates shown are the standard 2026 quarterly schedule and don't account for weekend/holiday shifts — verify the exact date on IRS.gov before paying.

Worked example

A single filer in Texas expecting $100,000 in net profit for the year, with no prior-year liability, owes roughly $22,900/year under the 90%-safe-harbor rule — about $5,700 per quarter. If they've paid nothing by Q2, the calculator flags underpayment penalty risk and shows the full two-quarter catch-up amount due.

Limitations

• Due dates shown are the standard calendar and don't adjust for weekends or federal holidays in a given year — always confirm the exact date on IRS.gov before paying.
• State estimated-tax rules (their own safe-harbor percentages and due dates) aren't modeled — this only computes the federal + partial-state estimate.
• Doesn't account for uneven income across the year (e.g., a big Q4 payment) — the annualized-income installment method, which can reduce early-quarter payments for lumpy income, isn't implemented.