What this includes, and what it does not

The figure covers federal self-employment tax and federal income tax on your net profit, after the deduction for half of self-employment tax and the qualified business income deduction. It uses the 2026constants listed on the methodology page, each one read from an IRS source and dated.

It does not include state income tax except for the nine states that levy none, and it does not include credits, itemised deductions or carryovers. Those move the number, sometimes a lot.

Three things it gets right that most do not

The 92.35% adjustment. Only that share of net profit is subject to self-employment tax, because the employer-equivalent half of 15.3% comes out first. Calculators that skip it overstate the bill by roughly 8%.
The wage-base ceiling. The Social Security portion stops at $184,500 of earnings for 2026. Medicare has no ceiling and keeps going.
The new 2026 QBI minimum. From this tax year, at least $1,000 of qualified business income earns a deduction of at least $400 even where the ordinary 20% computation gives less. Almost nothing on the market models this yet.

Why the amount is not simply 30%

The 30% rule of thumb over-reserves badly at low income, where the standard deduction absorbs most of the profit, and under-reserves at high income, where the 32% and 35% brackets start to bite. Change the income above and watch the effective rate move — that spread is the whole argument against a flat percentage.

Get reminded before each deadline

Four emails a year, roughly ten days before each payment is due. Missing one is almost always an oversight rather than a decision.

Figures on this page are checked against the primary source cited for each one, and the calculations behind them are covered by automated tests. No credentialed tax professional has reviewed this page. Treat it as a well-sourced starting point, not as a substitute for advice on your own situation.