Know what to set aside, and what to pay each quarter

What it calculates

• Self-employment tax. 15.3% on 92.35% of your profit: 12.4% Social Security, up to the 2026 wage base of $184,500 (less any W-2 wages), plus 2.9% Medicare.
• Additional Medicare Tax. 0.9% above $200,000 ($250,000 married filing jointly, $125,000 married filing separately).
• Federal income tax. 2026 brackets and standard deduction for your filing status, after deducting half your self-employment tax, SE health insurance and retirement contributions.
• Qualified business income (QBI) deduction. 20% of business income, capped at 20% of taxable income. Above the 2026 threshold it phases out over $75,000 ($150,000 joint), faster for “specified service” businesses such as consulting, health or law, assuming you pay no W-2 wages.
• Safe harbor. You generally avoid the underpayment penalty if you pay, on time each quarter, at least the smaller of 90% of this year's tax or 100% of last year's. That's 110% if your 2025 AGI was over $150,000 ($75,000 married filing separately).
• Payment schedule. The four 2026 due dates, with a column to record what you've paid.

The 2026 figures it uses

The file lists all seven brackets for each filing status, with sources: Rev. Proc. 2025-32, the 2026 Form 1040-ES and the Form 8995 instructions. Every figure was checked against these documents in October 2026.

What it leaves out

• State and local income tax.
• Tax credits such as the child tax credit. With credits you'd owe less.
• QBI wage and property limits. If you earn above the threshold and pay employees or own business property, your deduction may be bigger and your tax lower.
• The 3.8% net investment income tax and the alternative minimum tax. If they apply to you, the estimate will be too low.
• The new 2026 charitable deduction for people who don't itemize, and the $400 minimum QBI deduction. Both would lower your tax slightly.
• Lower rates on long-term capital gains and qualified dividends.
• The 2025–2028 deductions for tips, overtime, seniors and car loan interest. Enter them yourself if they apply.

This is a planning estimate, not tax advice. If your situation isn't simple, have a tax professional check it. To track the income and expenses behind it, use the bookkeeping template.