How quarterly estimated taxes work
When you work for an employer, tax comes out of every paycheck. When you work for yourself, nobody withholds it, but the IRS still expects to be paid as the year goes, not all at once in April. So you send estimated payments four times a year, each covering roughly a quarter of the year's tax.
That tax has two parts. Self-employment tax is Social Security and Medicare, 15.3% on 92.35% of your profit. Income tax is the same tax employees pay, worked out on your profit after half of the self-employment tax, the standard deduction and the 20% qualified business income deduction.
How this calculator gets your number
- Self-employment tax: 12.4% Social Security (up to the wage base) plus 2.9% Medicare on 92.35% of your profit, and 0.9% more on high earnings.
- Half of the Social Security and Medicare tax comes off your income.
- The 2026 standard deduction for your filing status comes off next.
- The qualified business income deduction takes 20% off what's left, within the IRS limits.
- The 2026 federal brackets give your income tax.
- Self-employment tax plus income tax, divided by four, is your quarterly payment.
The 2026 numbers this calculator uses
| Self-employment tax rate | 15.3% on 92.35% of profit |
| Social Security wage base | $184,500 |
| Additional Medicare tax | 0.9% above $200,000 ($250,000 joint) |
| Standard deduction (single / joint / head of household) | $16,100 / $32,200 / $24,150 |
| Qualified business income deduction | 20%, at least $400 |
| Standard mileage rate | 72.5¢ Jan–Jun, 76¢ from Jul 1 |
From IRS Rev. Proc. 2025-32 and the Social Security Administration's 2026 figures.
Questions
Who has to pay quarterly estimated taxes?
Generally anyone who expects to owe $1,000 or more in federal tax when they file, after withholding and credits. Most freelancers, independent contractors and gig workers with a profit do, because no employer is withholding tax from their pay.
When are 2026 quarterly taxes due?
April 15, June 15 and September 15, 2026, and January 15, 2027. When a date falls on a weekend or a federal holiday, it moves to the next business day.
What happens if I pay too little?
The IRS charges an underpayment penalty, worked out like interest on each payment that was late or short (Form 2210). You avoid it by paying at least 90% of this year's tax, or 100% of last year's tax (110% if last year's AGI was over $150,000), spread across the four deadlines.
How accurate is this calculator?
It uses the IRS's 2026 rates for one source of self-employment income and the standard deduction. It leaves out state tax, W-2 wages, credits and deductions such as health insurance or retirement contributions, so treat it as an estimate, not tax advice.
Also free: Self-employment tax calculator.