The US tax system is pay-as-you-go. W-2 employees satisfy this through paycheck withholding. Self-employed individuals, business owners, landlords, and investors with significant income have to satisfy it through quarterly estimated payments — or face underpayment penalties when they file.
Who needs to pay
You generally need to make estimated tax payments if you expect to owe at least $1,000 in federal tax after subtracting withholding and refundable credits. This catches:
- Freelancers, consultants, and independent contractors
- Small business owners (sole proprietors, LLC members, S-Corp shareholders)
- Real estate investors with rental income
- Investors with significant capital gains or dividends
- Retirees with pension, Social Security, or investment income not covered by withholding
The four payment dates
Quarterly payments are due four times a year, though they don't align perfectly with calendar quarters:
- April 15 — for income earned January 1 through March 31
- June 15 — for income earned April 1 through May 31
- September 15 — for income earned June 1 through August 31
- January 15 (following year) — for income earned September 1 through December 31
When a due date falls on a weekend or federal holiday, the deadline shifts to the next business day.
How to calculate the right amount
There are two safe-harbor methods that protect you from underpayment penalties:
- 100% of last year's tax — Pay at least 100% of what you owed in total federal income tax the prior year (110% if your prior-year AGI exceeded $150,000). Divide that amount by four. This method works regardless of income fluctuation and gives you certainty.
- 90% of this year's estimated tax — Estimate your actual current-year liability and pay 90% of it through withholding and estimated payments. Requires ongoing income tracking.
Method 1 is usually simpler and safer for people with variable income. Method 2 can result in smaller payments in a down year — but underpaying exposes you to penalties.
Making the payments
The easiest method is IRS Direct Pay (irs.gov/payments) — no account setup required, direct debit from your bank. You can also use EFTPS (the Electronic Federal Tax Payment System) for scheduled, recurring payments. Most states have their own estimated tax requirements with separate payment systems.
The penalty for getting it wrong
The underpayment penalty is calculated quarterly at the federal short-term interest rate plus 3 percentage points. In recent years that has been roughly 7-8% annually on the underpaid amount. It's not catastrophic, but it's also an entirely avoidable cost.
