US Quarterly Tax Calculator

How freelance quarterly taxes actually work in the US

If you earn more than $400 in self-employment income in a year, the IRS expects you to pay estimated taxes quarterly — not in one lump sum at filing time. Underpaying these triggers penalties (currently ~8% APR on the shortfall) plus interest, even if you file and pay the full amount on April 15.

You owe two distinct federal taxes on freelance income: (1) self-employment tax (15.3%, covering both halves of Social Security and Medicare), and (2) regular income tax (10-37% based on bracket). Plus state income tax in 41 states (the 9 with no income tax: AK, FL, NV, NH, SD, TN, TX, WA, WY). The calculator above estimates all three.

• Self-employment tax: 15.3% on 92.35% of net earnings, up to $176,100 (2025); 2.9% on the rest, no cap.
• Federal income tax: 10-37% based on bracket. Standard deduction reduces taxable income.
• State tax: 0-13.3% depending on state. The calculator uses the top marginal rate as a rough estimate.
• Half of SE tax is deductible: lowers your federal income tax. The calculator handles this automatically.
• No quarterly = penalty: currently ~8% APR on the shortfall. Even if you pay the full amount in April, you owe penalties for underpayment during the year.

The four quarterly due dates (don't miss them)

IRS quarterly estimated payment due dates are NOT calendar quarters. They're weird:

Q1: April 15 (covers Jan-Mar income) Q2: June 15 (covers Apr-May income — only 2 months!) Q3: September 15 (covers Jun-Aug income) Q4: January 15 of next year (covers Sep-Dec income)

Q2 is the trap — only 2 months of income but a full quarterly payment. Many freelancers underpay Q2 because they didn't realize the period was shorter and the payment was due so soon after Q1. If a due date falls on a weekend or holiday, the next business day applies.

You can pay online at IRS Direct Pay (free, takes 5 minutes) or via EFTPS, or mail a check with Form 1040-ES. Don't mail it — payments take 7-10 days to clear, missed deadlines accrue penalties from the original due date.

• Q1 — April 15: covers income from January 1 to March 31.
• Q2 — June 15: covers income from April 1 to May 31. (Only 2 months — easy to underpay.)
• Q3 — September 15: covers income from June 1 to August 31.
• Q4 — January 15: covers income from September 1 to December 31. Of the *following* year.
• Pay online: IRS Direct Pay (free, instant) or EFTPS. Avoid mailing — too slow.

The safe harbor rule (your get-out-of-penalty card)

You can avoid underpayment penalties even if you owe a big balance at filing time, IF you meet the safe harbor: pay 100% of last year's total tax liability (110% if your AGI was over $150K), divided into 4 equal quarterly payments.

This is the easy mode for freelancers with volatile income. Instead of estimating this year (which you don't know yet), just pay last year's number. If your income drops, you'll get a refund. If it rises, you'll owe extra at filing — but no penalty, because you met the safe harbor.

The alternative is the 90% rule: pay 90% of THIS year's actual liability. Risky for new freelancers because you have to estimate accurately as the year unfolds. Most freelancers use safe harbor for years 2+, and the 90% rule for year 1 (since you have no last year).

• Safe harbor — 100% rule: pay last year's total tax / 4 each quarter. Penalty-proof.
• Safe harbor — 110% rule: if your AGI > $150K last year, you must pay 110% of last year's tax to qualify.
• 90% rule: pay 90% of this year's actual liability. Riskier but possibly lower if income dropped.
• Use the lower of the two: safe harbor BY LAST YEAR vs 90% OF CURRENT YEAR — whichever is lower is your minimum quarterly payment.
• Year 1 freelancer: no last year to use; must use the 90% rule and re-estimate quarterly.

Deductions that reduce your tax bill

Every legitimate business expense reduces your net SE income, which reduces both your SE tax AND your income tax. The most common freelancer deductions: home office (simplified method: $5/sqft up to 300 sqft = $1,500 max), health insurance premiums (above-the-line, very valuable), retirement contributions (Solo 401k up to $23,000 employee + 25% employer; or SEP IRA 25% of net earnings up to $69,000), business meals (50%, with receipt), business travel (100%), professional services (accountant, lawyer), software & subscriptions, equipment (Section 179 lets you write off the whole thing in year of purchase up to limits), continuing education, and 50% of SE tax (automatic, calculator handles this).

Don't try to deduct things you don't have receipts for. The IRS audits Schedule C with above-average frequency (3-5x higher than W-2 returns) and will require documentation if challenged.

• Home office: $5/sqft simplified, up to 300 sqft = $1,500 max. Or actual-expense method if you have records.
• Health insurance: above-the-line deduction for self-employed. Reduces AGI directly.
• Retirement (Solo 401k): up to $23,000 employee + 25% of net earnings as employer = up to ~$70K total tax-deferred.
• SEP IRA alternative: 25% of net earnings, up to $69,000 (2024). Simpler than Solo 401k but lower cap.
• Section 179 equipment: deduct full cost of laptop / equipment in year of purchase, up to limits.
• 50% of SE tax: automatic deduction from gross income. Calculator above includes this.

Setting up a "tax savings" sub-account

The single best habit for freelancers: every time you receive a payment, immediately move 25-30% to a separate savings account labeled "Taxes". This is non-negotiable. The money is not yours; it's the IRS's, you're just holding it.

Banks like Ally, SoFi, and Wise let you create labeled sub-accounts inside your main account. Set up automatic transfer rules: "every deposit > $X moves Y% to Tax Savings". Some accounting software (Wave, FreshBooks, QuickBooks) has built-in tax estimation that auto-allocates as invoices are paid.

Pay each quarterly estimate from this sub-account. At year-end you'll either have a small surplus (refund will come) or a small deficit (true up at filing). Either way you'll never be in the panic-zone of "tax day is 30 days away and I have nothing saved".

• Move 25-30% per payment: most freelancers under-save. 30% covers federal + SE + most state combinations.
• Separate account, not just a label: mental separation isn't enough. Move it physically.
• Pay quarterly from this account: no other money mixed in. Simplifies bookkeeping.
• High-yield savings: 4-5% APY on the parked tax money is essentially free side income.