How to use the quarterly tax calculator
- 1Enter your expected net profit from self-employment for all of 2026: 1099 and business income minus business expenses.
- 2Add any W-2 wages and other taxable income, and choose your filing status.
- 3Enter the federal tax you expect to have withheld in 2026 and any estimated payments already made, then choose how many payments are left this year.
- 4Leave the QBI deduction on if your business qualifies. Add last year’s total tax to see the safe harbor minimum.
- 5Read the amount to pay each quarter, the breakdown of your 2026 tax and the due dates.
Who pays quarterly estimated tax, and when
Nobody withholds tax from 1099 or self-employment income, so the IRS expects you to pay it during the year in four estimated payments with Form 1040-ES. You generally need to pay if you expect to owe $1,000 or more for 2026 after withholding and credits.
For tax year 2026 the payments are due April 15, 2026, June 15, 2026, September 15, 2026 and January 15, 2027. You can skip the January payment if you file your 2026 return by February 1, 2027 and pay the whole balance with it. If a due date falls on a weekend or legal holiday, it moves to the next business day.
If you start making money partway through the year, divide what you still owe by the payments left. The calculator does this when you set the number of payments remaining.
Each payment = (Total 2026 tax − Withholding − Payments already made) ÷ Payments left
How the calculator works out your 2026 tax
It starts with self-employment tax: 15.3% (12.4% Social Security up to the $184,500 wage base, less any W-2 wages, plus 2.9% Medicare) on 92.35% of your profit. Half of that is deducted from your income.
Your adjusted gross income, less the 2026 standard deduction ($16,100 single, $32,200 married filing jointly, $24,150 head of household) and the QBI deduction, gives taxable income. Income tax uses the 2026 brackets, from 10% up to 37%. Additional Medicare Tax of 0.9% is added if your earnings pass $200,000 ($250,000 married filing jointly).
SE tax = 15.3% × Profit × 92.35% (Social Security part capped) AGI = Profit + Wages + Other income − SE tax ÷ 2 Taxable income = AGI − Standard deduction − QBI deduction Total tax = Income tax (2026 brackets) + SE tax + Additional Medicare Tax
The 2026 brackets used
Single: 10% to $12,400, 12% to $50,400, 22% to $105,700, 24% to $201,775, 32% to $256,225, 35% to $640,600 and 37% above. Married filing jointly: 10% to $24,800, 12% to $100,800, 22% to $211,400, 24% to $403,550, 32% to $512,450, 35% to $768,700 and 37% above. Head of household: 10% to $17,700, 12% to $67,450, 22% to $105,700, 24% to $201,750, 32% to $256,200, 35% to $640,600 and 37% above.
Brackets, standard deductions and QBI thresholds are from IRS Revenue Procedure 2025-32, which includes the One Big Beautiful Bill Act changes. The wage base is from the Social Security Administration and the due dates and safe harbor rules from the 2026 Form 1040-ES. All were checked November 2026.
Safe harbor: the least you can pay without a penalty
You avoid the underpayment penalty if your withholding and estimated payments, paid on time, cover the smaller of 90% of your 2026 tax or 100% of your 2025 tax. If your 2025 adjusted gross income was over $150,000 ($75,000 if married filing separately), the second figure is 110% of your 2025 tax.
Paying on the safe harbor protects you from the penalty, not from the bill: anything you have not paid is still due by April 15, 2027. If your income is rising, the prior-year rule lets you pay less now, but set the difference aside.
Required annual payment = the lower of (90% × 2026 tax, 100% or 110% × 2025 tax)
The QBI deduction and what this estimate leaves out
The qualified business income deduction lets many sole proprietors and pass-through owners deduct 20% of business profit. The calculator uses a simple version: 20% of profit after the self-employment tax deduction, limited to 20% of taxable income before the deduction. Above $201,750 of taxable income ($403,500 married filing jointly), limits for wages paid, property and specified service businesses such as consulting, law and health can reduce it, so check with a tax adviser.
The estimate does not include state or local income tax, tax credits such as the child tax credit, itemized deductions, capital gains rates, retirement contributions, the self-employed health insurance deduction or the new 2025–2028 deductions for tips, overtime and seniors. Each of these can change your bill, so treat the result as a planning figure.
QBI deduction = 20% × the lower of (Profit − SE tax ÷ 2, Taxable income before QBI)
Worked example
A single freelance developer expects $80,000 of net profit in 2026, has no other income or withholding and qualifies for the QBI deduction.
| Self-employment tax ($80,000 × 92.35% × 15.3%) | $11,303.64 |
| Adjusted gross income ($80,000 − $5,651.82) | $74,348.18 |
| Standard deduction | $16,100.00 |
| QBI deduction (20% of $58,248.18) | $11,649.64 |
| Taxable income | $46,598.54 |
| Income tax (10% and 12% brackets) | $5,343.83 |
| Total 2026 federal tax | $16,647.47 (20.8% of profit) |
| Each quarterly payment | $4,161.87 |
The developer pays $4,161.87 on April 15, June 15 and September 15, 2026 and January 15, 2027. Without the QBI deduction the tax would be $18,830.24, or $4,707.56 a quarter. If their 2025 tax was $12,000, paying $3,000 a quarter would meet the safe harbor, with the remaining $4,647.47 due in April 2027.