The 4 quarterly deadlines.
Two ways to avoid the penalty.
Method 1: 100% of last year
Pay 100% of last year's total tax bill (110% if AGI > $150K). Simplest if your income is similar year-over-year.
Method 2: 90% of current year
Pay 90% of what you'll actually owe this year. Better if your income is dropping.
Common questions.
Do I need to pay quarterly estimated tax?
Generally yes if you expect to owe $1,000+ in tax for the year (after withholding/credits). Common for self-employed, freelancers, LLC/S-Corp owners, investors with capital gains.
What is the underpayment penalty?
Calculated quarter-by-quarter at the federal short-term rate + 3%. Recent rate around 8% annualized.
What about state quarterly taxes?
Most states with income tax require their own quarterly payments. Some align with federal dates; some have different schedules.
What if I have a W-2 job too?
Your W-2 withholding counts toward the safe-harbor.
How do I pay?
Federal: IRS Direct Pay, EFTPS, or Form 1040-ES voucher. State: usually state portal or mailed voucher.
Can I pay all at once at year-end?
Technically no — the penalty applies per quarter even if you pay all by Jan 15.
What about S-Corp owners?
S-Corp distributions are not subject to SE tax but are taxable as ordinary income. Plan quarterly to cover that.
Annualized income method?
For uneven income (consulting, capital gains), use Form 2210 Schedule AI to annualize.
Can I skip Q4?
Some taxpayers skip Q4 if they file by Jan 31 with full payment.