Calculators
Quarterly estimated tax, for 2026.
Federal, state and self-employment tax on a net profit, a job, and what was already withheld. The four payments below, with dates. The same arithmetic the app runs on a real ledger, run here on the numbers you type.
Your situation
Nothing typed here leaves your browser. The figures on the right recompute as you type.
Estimated 2026 tax
10.0% marginalThe four payments
Nothing is required this year on these figures.
A quarter of 90% of this year’s tax, each date, after withholding. Add last year’s total tax in the app and this becomes the full safe-harbor test: the lesser of that and 100% (110% above $150,000) of what you owed last year.
How this is computed
- Self-employment tax on 92.35% of net profit: 12.4% Social Security up to the wage base, plus 2.9% Medicare.
- Half of that self-employment tax deducted back above the line, before federal tax is figured.
- A 20% qualified business income (QBI) deduction on what's left, the same as the return allows.
- The single standard deduction, on the federal side.
An estimate of what to set aside, not a filed return. It excludes itemized deductions, retirement contributions and credits.
On your real books
Contha runs this same engine on your actual transactions.
Connected accounts instead of typed guesses, a reserve that says whether the tax money is really there, the four payments recorded as you send them, and a year-end package your accountant opens without an account.
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