How this tax estimator works
The math follows the same path your tax return does. Start with gross income, subtract pre-tax retirement contributions (401(k), traditional IRA) and the standard deduction for your filing status, and what's left is taxable income. That taxable income is run through the seven federal brackets for tax year 2026 — each slice of income taxed at its own rate — then the child tax credit ($2,200 per qualifying child under 17) comes off the result. If you tell it what's being withheld from your paychecks, it also plays refund estimator: withholding above the estimated tax is your projected refund, withholding below it is the check you'll write in April.
Every figure comes from IRS Revenue Procedure 2025-32 (released October 2025), cross-checked against the Tax Foundation's published 2026 tables — not last year's numbers with a guess on top.
The formula
Federal tax = Σ (income in each bracket × that bracket's rate) − Child tax credit
Gross income is your pay before anything is taken out; pre-tax contributions are retirement dollars that skip federal tax now; the standard deduction is the no-questions-asked amount everyone subtracts ($16,100 single, $32,200 married filing jointly, $24,150 head of household for 2026). The bracket sum is the heart of it: your first dollars are taxed at 10% no matter how much you earn, and only the dollars inside each higher bracket pay that bracket's rate.
Worked example
A single filer earns $60,000 and puts $3,000 into a traditional 401(k). Taxable income: $60,000 − $3,000 − $16,100 standard deduction = $40,900.
The first $12,400 is taxed at 10% ($1,240); the remaining $28,500 falls in the 12% bracket ($3,420). Estimated federal tax: $4,660 — a 7.8% effective rate, even though the marginal bracket is 12%. If this filer's expected full-year withholding is $5,500, the projected refund is $840.
The 2026 federal tax brackets
For tax year 2026 (the return you file in early 2027), the taxable-income brackets are:
| Rate | Single | Married filing jointly | Head of household |
|---|---|---|---|
| 10% | $0 – $12,400 | $0 – $24,800 | $0 – $17,700 |
| 12% | $12,400 – $50,400 | $24,800 – $100,800 | $17,700 – $67,450 |
| 22% | $50,400 – $105,700 | $100,800 – $211,400 | $67,450 – $105,700 |
| 24% | $105,700 – $201,775 | $211,400 – $403,550 | $105,700 – $201,750 |
| 32% | $201,775 – $256,225 | $403,550 – $512,450 | $201,750 – $256,200 |
| 35% | $256,225 – $640,600 | $512,450 – $768,700 | $256,200 – $640,600 |
| 37% | Over $640,600 | Over $768,700 | Over $640,600 |
Source: IRS Rev. Proc. 2025-32, cross-checked against the Tax Foundation's 2026 bracket tables. (Spot the trivia: the head-of-household 24% bracket tops out at $201,750 — $25 lower than single's $201,775. Inflation-adjustment rounding produces genuinely odd corners.) The brackets apply to taxable income, after the standard deduction — so a single filer doesn't pay a cent of federal income tax until gross income clears $16,100.
"I don't want the raise — it'll bump my tax bracket"
This myth costs real people real money, so let's kill it with arithmetic. A single filer with $45,900 of taxable income sits near the top of the 12% bracket and gets a raise that pushes taxable income to $55,900 — $5,500 of it lands in the 22% bracket. Here's what actually happens:
Tax before the raise: $1,240 + 12% × $33,500 = $5,260.
Tax after: the first $50,400 is taxed exactly as before, and only the $5,500 above the line pays 22%. New tax: $7,010.
The $10,000 raise cost $1,750 in tax — $8,250 stays in your pocket. Not one dollar of the old income was taxed differently.
A raise can never shrink your take-home pay through the tax brackets, period. (Income-tested benefits and credit phase-outs can create genuine cliffs, but that's a different mechanism — the brackets themselves have no cliffs at all.) If you're weighing a raise or comparing job offers, the hourly to salary calculator pairs well with this one.
Marginal vs. effective rate
Your marginal rate is the bracket your last dollar lands in — what you'd pay on one more dollar of income. Your effective rate is total tax divided by total income — what you actually pay overall, and it's always lower, because your earlier dollars were taxed at 10% and 12% (and the first chunk at 0%, thanks to the standard deduction). The $60,000 filer above is "in the 12% bracket" but pays 7.8% of gross income in federal tax. When someone says "I lose a third of my paycheck to federal income tax," they're almost always quoting a marginal rate — or including FICA and state tax — not their federal effective rate.
Standard vs. itemized, honestly
Itemizing only makes sense when your deductible expenses — mortgage interest, state and local taxes (capped), charitable gifts, large medical bills — add up to more than the standard deduction, and for roughly nine in ten filers they don't. The 2026 standard deduction of $16,100/$32,200 is a high bar to clear, and that's the honest reason this calculator doesn't ask for your receipts: for most people, itemizing is a spreadsheet detour to the same answer. If you have a big mortgage in a high-tax state or made major charitable gifts, your tax may come out lower than estimated here — a pleasant direction to be wrong in.
What this estimate leaves out
Being clear about the edges matters more on a tax page than anywhere else. This estimator covers federal income tax only. It does not include: state income tax (0% in nine states, over 13% at the top in California); FICA payroll taxes — another 7.65% of wages for employees (6.2% Social Security + 1.45% Medicare), taken out before you ever see it; self-employment tax — freelancers pay both halves of FICA, which is what the quarterly tax calculator handles; capital gains, which have their own rate schedule covered by the capital gains tax calculator; and itemized deductions or credits beyond the child tax credit. The credit here is applied as nonrefundable (it can zero out your tax but not go below zero) — in reality up to $1,700 per child is refundable for lower-income filers, so the real bill can be even lower.
A refund is not a bonus
The happiest day of tax season deserves an honest footnote: a refund is your own money coming back after an interest-free loan to the Treasury. If you get $3,000 back every April, you over-withheld $250 a month all year — money that could have been earning interest or paying down debt, a cost the time value of money calculator can put a number on. There's nothing wrong with using withholding as forced savings if that's a deliberate choice. Just make it deliberate: enter your actual withholding above, see where you'll land, and adjust your W-4 if the gap in either direction surprises you.