The US tax system runs on pay-as-you-go. W-2 employees do this automatically through paycheck withholding. Freelancers, contractors, and self-employed business owners do it manually through four estimated payments per year. The mechanics sound bureaucratic but the rules are actually simple, and getting them right protects you from the underpayment penalty that quietly stings a lot of new freelancers.
When quarterly payments are due
The four 2026 due dates are April 15 (January-March income), June 15 (April-May), September 15 (June-August), and January 15, 2027 (September-December). June 15, 2026 is a Monday, so Q2 does not shift. Notice the quarters are not equal - the second period is two months and the fourth is four. This is just how the IRS schedules it.
The two safe-harbor rules
The IRS will not assess an underpayment penalty if you meet either of two safe harbors. **Rule 1: 90% of current year.** Pay at least 90% of this year's actual total tax through quarterly payments and withholding. **Rule 2: 100% of prior year (110% if AGI > $150k).** Pay at least 100% (or 110% for high earners) of last year's total tax in equal installments. Most freelancers use Rule 2 because it is fixed in advance and, when paid on time, can satisfy the federal underpayment safe harbor even if income rises later. It does not limit the balance ultimately due with the return.
How to calculate each quarter
For the safe-harbor approach, take last year's total tax (line 24 on Form 1040), apply the 110% multiplier if applicable, and divide by four. That number is your quarterly payment, due on each of the four dates above. For the current-year approach, project this year's total income, run it through the 1099 Tax Calculator to get an estimated annual tax, and divide by the number of remaining quarters.
Who actually has to pay quarterly
You owe estimated payments if you expect to owe at least $1,000 in tax for the year after withholding and credits. Almost every full-time freelancer crosses that threshold. Side-hustlers with a primary W-2 job may be able to skip quarterly payments if they bump up W-2 withholding enough to cover the side-income tax - a useful trick because withholding is treated as paid evenly throughout the year regardless of when it actually happens.
What happens if you miss a payment
The underpayment penalty is calculated as interest on the shortfall, computed for each quarter you were short. It is not a fixed dollar amount - for typical freelance underpayments it works out to a few percent annually on the missed amount. Not catastrophic, but completely avoidable.
How to actually pay
Individuals can sign in to an IRS Online Account to make and track estimated payments, or use the Direct Pay guest path for a free bank-account payment. New individual EFTPS enrollments are closed; existing individual users can still pay there for now but must move to Online Account or Direct Pay later in 2026. Card and digital-wallet processors charge fees. State estimated payments are separate - most states with income tax have their own portal and schedule.
Tools and guides
The Quarterly Tax Estimator compares the prior-year and current-year methods and maps payments to the four IRS due dates. The 1099 Tax Calculator estimates the annual federal, self-employment, and state tax behind a current-year projection. The Self-Employment Tax Calculator isolates the Schedule SE portion. For the filing rules and a worked annualized-income example, read How to Pay Quarterly Estimated Taxes.