EstTaxLab

Quarterly Estimated Tax Calculator

A free 2026 quarterly estimated tax calculator for freelancers and the self-employed, following the IRS Form 1040-ES method: self-employment tax of 15.3% on 92.35% of net profit, then federal income tax on income after the deductible half of SE tax and the standard deduction. A single filer with $90,000 of net profit owes $12,716.60 of SE tax plus $9,571.17 of income tax — $22,287.77 total, paid as four installments of $5,571.94. A safe-harbor view computes the minimum payments that avoid an underpayment penalty using last year's tax. Constants come from IRS Rev. Proc. 2025-32 and the 2026 Social Security wage base, with disclosed simplifications (standard deduction only, no QBI deduction or credits). A planning estimate — not tax advice or a filing tool.