This page is the contractor leftover tool. Enter net profit after ordinary and necessary expenses — not gross invoices. Choose filing status and state. The result is self-employment tax, extra Medicare if you are over the high-income line, federal income tax, a state planning amount, leftover, a set-aside percent of net, and that tax pile divided by four.
A worked case from the tests: $60,000 net, single, Texas. Self-employment tax is $8,477.73. State is $0. Federal income tax sits between $4,400 and $4,700. Set-aside is about 20–23% of net, not a flat 30%. Take-home is about $46,800–$47,400. Four equal quarters add back to the tax pile within a few cents.
A second case from this engine on 2026-09-21: $80,000 net, single, Texas. Self-employment tax is $11,303.64. Federal is $7,526.60. Total tax is $18,830.24. Take-home is $61,169.76. Set-aside is 23.5% of net. An equal quarter is $4,707.56. Same profit in California: state planning $5,417.08, total tax $24,247.32, take-home $55,752.68, set-aside 30.3%, quarter $6,061.83. Thirty percent is almost exactly the California case and too high for the Texas case. That is why this page prints a percent instead of a slogan.
Why this is not the paycheck tool
A W-2 job already withheld Social Security and Medicare, and the employer paid a match you never see. A 1099-NEC or Schedule C profit has nobody withholding unless you asked. April is a surprise only because the cash sat in the operating account. The IRS still wants estimated tax on Form 1040-ES during the year.
SE tax is 15.3% on 92.35% of net if net is at least $400. That is both halves. Half of the 15.3% comes off before we compute income tax. We do not apply QBI, a solo 401(k), health insurance, or a home office. If you have those, our set-aside is a ceiling.
The 30% rumor
SE tax alone is already about 14% of net after the haircut. Add federal brackets and a high-tax state and 30% is short. On a thin year in Texas, 30% is more than you need sitting idle. This page prints the percent it actually computed. Safe harbor (90% of this year or 100%/110% of last year) is still on the IRS form, not here.
Below $400 net we charge no SE tax and leftover equals the number you typed. Mix a day-job W-2 with a side 1099? Run both tools. Do not add the leftovers until you understand each stack.
Ads load only after a result. Official pages: IRS self-employment tax and Form 1040-ES. If last year’s return already has a large withholding from a W-2, say so to a CPA before you copy our quarterly figure onto a voucher. The 1040-ES guide walks the due dates using the $80,000 cases above.