Quarterly Estimated Taxes: A Simple Guide for Freelancers

Short answer: if you're self-employed and expect to owe $1,000+ in tax, the IRS wants you to pay estimated taxes four times a year — roughly April 15, June 15, September 15, and January 15. Skip them and you can owe an underpayment penalty, even if you pay in full by April.

Why quarterly payments exist

The US tax system is "pay as you go." Employees have tax withheld from every paycheck; the self-employed have to send it in themselves — in four installments across the year.

The 2026 deadlines

• Q1 (Jan 1 – Mar 31): due ~April 15
• Q2 (Apr 1 – May 31): due ~June 15
• Q3 (Jun 1 – Aug 31): due ~September 15
• Q4 (Sep 1 – Dec 31): due ~January 15 of the next year

(Dates shift slightly for weekends/holidays.)

How to calculate each payment

1. Estimate your net profit for the year (revenue − business expenses).
2. Apply your effective rate — most solo founders use 25–35% (see our guide on setting aside taxes).
3. Divide by four. Pay that each quarter.

Avoid the penalty with "safe harbor"

You generally dodge the underpayment penalty if you pay at least 90% of this year's tax, or 100% of last year's (110% if your prior-year income topped $150,000), in equal installments.

Make it painless

Set aside your tax % the moment each payment lands, keep it in a separate account, and get a reminder before each quarterly date. FounderFi does all three — set-aside math on your real numbers plus deadline reminders so a due date never sneaks up.

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Educational guidance, not licensed tax advice. Confirm your situation with a CPA.