Quarterly Estimated Tax Calculator
Your numbers
No lead-gen forms, no email wall — the complete federal answer, free. We compute the payment that makes you penalty-proof, which is usually less than your actual tax.
Revenue minus business expenses — your Schedule C bottom line
Line 24, "total tax," on your 2025 Form 1040 — NOT your refund or your withholding. Blank = we use the 90% method only
How we calculate this
The question this tool answers isn't "what's my tax" — it's "what do I pay each quarter so the IRS can't penalize me." Those are different numbers, and the difference is the safe harbor: pay either 90% of this year's projected tax or 100% of last year's total tax (110% if last year's AGI topped $150,000), whichever is less, and you're penalty-proof no matter what April brings.
The projection walks Form 1040-ES in order. Self-employment tax first: 15.3% on 92.35% of your net profit — but the 12.4% Social Security piece stops at the $184,500 wage base, and if a W-2 job already used up part of that base, your side income uses only what's left. High earners add the 0.9% Additional Medicare surtax. Half your SE tax comes back off your income, then the 20% QBI deduction (we model the simple case below the $201,750/$403,500 thresholds; above them we omit it, which errs on the safe side), then the 2026 brackets on what remains.
Withholding is the side-hustler's cheat code. Anything withheld from a W-2 paycheck counts toward the harbor, and the IRS treats it as paid evenly through the year — even a December withholding boost covers earlier quarters. Many people with day jobs need only tiny vouchers, or none at all: if your balance after withholding is under $1,000, no estimated payments are required, period.
Starting mid-year? Two 2026 deadlines have already passed. Pay the missed quarters' share with your next voucher — penalties accrue quarter by quarter and stop accruing on what you've paid. We don't compute the penalty itself (that's Form 2210); we get you onto the schedule that stops it.
Most tools in this space are lead-gen traps — a teaser number behind an email wall. This one is the complete federal answer, free. What it deliberately doesn't model is listed in the assumptions panel: state estimated taxes, itemized deductions, investment income, credits, and the annualized-income method for seasonal earners.
Real scenarios
Full-time freelancer, $100k profit: $5,032 a quarter
Projected total tax is $22,365 — SE tax $14,130, income tax $8,235 after the ½-SE and QBI deductions. But the safe harbor only requires 90% of that: $20,128, or $5,032 a quarter. The $2,237 difference rides until April, in your account instead of the Treasury's.
Side-hustler, $80k job + $30k freelance: $360 a quarter
The W-2 withholding of $9,500 counts toward the harbor and the job's wages absorb Social Security wage base first. Result: total projected tax of $12,155, harbor of $10,940 — and after withholding, vouchers of just $359.97. Most side-hustlers who fear quarterly taxes owe far less than they think.
Income dropped? The 90% prong is your friend
A freelancer who made $180k last year (total tax $25,000) but projects $60k this year would pay $27,500 on the 110% prior-year harbor — versus $10,833 on the 90% current-year prong. Same penalty protection, $16,667 less cash out the door. The tradeoff: if income recovers, re-run and adjust; the prior-year harbor never moves.