Quarterly estimated tax calculator

How Quarterly Estimated Tax Works

This calculator uses a simplified planning model that may help freelancers think through cash flow before filing a tax return. The IRS generally requires self-employed people to account for income tax and self-employment tax when they have net earnings from self-employment. In practice, your estimated tax may be affected by filing status, other household income, retirement contributions, deductions, credits, state rules, and timing. Because the tool cannot see your complete tax file, it uses transparent assumptions and displays the IRS source beside the result.

For federal income tax, the model applies the 2026 standard deduction and marginal brackets published by the IRS. Marginal brackets mean only income inside each band is estimated at that band rate. For self-employment tax, the model follows the broad Schedule SE pattern: net self-employment income is multiplied by 92.35%, then the 15.3% self-employment tax rate is applied. One-half of the estimated self-employment tax is treated as an adjustment when estimating income tax. This is intended to mirror the common planning sequence, but actual return preparation may include additional lines, limits, and worksheets.

The state estimate is intentionally conservative and simplified. It applies an approximate top or flat state rate to adjusted income, rather than reproducing every state-specific deduction, credit, locality, or apportionment rule. Your estimated tax may therefore be higher or lower than what a state return would show. Use the output as a planning conversation starter, not as filing instructions. Before sending payments or making business decisions, review IRS guidance and speak with a qualified CPA who can evaluate your specific records.