The U.S. tax system is pay-as-you-go. Employees never notice because withholding does it for them. The moment you're self-employed, a landlord, or earning meaningful income without withholding, the IRS expects you to send money in four times a year — and charges penalties when you don't.
Who actually has to pay
You generally need to make estimated payments if you expect to owe $1,000 or more when you file, and your withholding won't cover it. In practice that's:
- Freelancers, contractors, and gig workers
- Small business owners and partners
- Landlords with rental profit
- Anyone with significant investment or side income
The four deadlines
Estimated taxes follow the IRS's own calendar, not neat quarters (dates shift slightly for weekends and holidays):
| Income period | Typical due date |
|---|---|
| January 1 – March 31 | April 15 |
| April 1 – May 31 | June 15 |
| June 1 – August 31 | September 15 |
| September 1 – December 31 | January 15 (next year) |
How much to send: the safe-harbor shortcut
You don't have to predict your year perfectly. The IRS won't penalize you if you pay in at least 90% of this year's actual tax, or 100% of last year's total tax (110% if your prior-year adjusted gross income was over $150,000).
That second option — the safe harbor — is the workhorse. Take last year's total tax, divide by four, automate the payments, and you're penalty-proof even if this year turns out bigger. You'll settle the difference at filing, but without penalties riding on it.
The mistakes we fix most often
- Skipping payments in a good year — the penalty is calculated per quarter; catching up in Q4 doesn't erase Q1–Q3.
- Forgetting North Carolina — NC has its own estimated payments (Form NC-40) on a similar schedule, and other states work the same way.
- Paying from the personal account with no records — clean books make the year-end reconciliation painless.
- Treating estimates as optional in year one of a business — the first year is exactly when surprise balances plus penalties show up.
Make it boring
The goal is for estimated taxes to be a non-event: a fixed, automated payment you never think about, sized once a year when we plan. If you got an underpayment penalty last filing season — or you're guessing at your payments — that's fixable in one conversation.