What’s coming
back from the IRS.

Field guide

How a tax refund (or bill) is actually calculated.

A tax refund isn’t a gift from the government — it’s your own money coming back. Every pay period your employer withholds federal income tax based on the W-4 form you filed when you started the job. At year end you file a return, calculate what you actually owed, and the difference settles: overpay → refund, underpay → balance due.

Step 1: Gross income to taxable income

The path starts with your W-2 Box 1 wages — your total federal taxable wages for the year. From there:

1. Subtract pre-tax contributions (traditional 401(k), HSA, FSA, traditional IRA) to reach Adjusted Gross Income (AGI). These dollars reduce your taxable income dollar-for-dollar.
2. Subtract your deduction — either the standard deduction or itemized total (whichever you claim) — to reach taxable income. The 2026 standard deductions are $16,100 (single), $32,200 (married jointly), and $24,150 (head of household).

Step 2: Apply the progressive brackets

U.S. federal tax is marginal: only the income that falls within each bracket is taxed at that bracket’s rate. A single filer with $75,000 in taxable income does not pay 22% on all $75,000 — only on the slice above $50,400.

This calculator runs all seven 2026 brackets for your filing status and sums the result automatically.

Step 3: Subtract the Child Tax Credit

If you have qualifying children under 17, you may claim the Child Tax Credit (CTC) — up to $2,000 per qualifying child in 2026. Unlike deductions (which reduce taxable income), credits reduce your tax bill dollar-for-dollar.

The CTC phases out by $50 for every $1,000 of income above $200,000 (single / head of household) or $400,000 (married jointly). Enter your qualifying dependents and the calculator applies the phase-out automatically.

Step 4: Compare with withholding

Your employer remitted estimated tax on your behalf throughout the year based on your W-4 elections. Your W-2 Box 2 shows the total federal income tax withheld. The final step is simple subtraction:

A positive result is your refund. A negative result is what you owe when you file by April 15.

Worked example

Single filer, $75,000 W-2 income, $8,000 withheld, no dependents, standard deduction:

1. Standard deduction: $16,100 → Taxable income: $58,900
2. 10% on $12,400 = $1,240  |  12% on $38,000 = $4,560  |  22% on $8,500 = $1,870
3. Total tax: $7,670  |  CTC: $0
4. Withheld $8,000 − Tax $7,670 = $330 refund

Standard vs. itemized deduction

You choose the larger of the two each year — there’s no requirement to itemize. Most filers take the standard deduction post-2017 because it’s larger than what they can itemize. Itemizing makes sense if you have large mortgage interest, state and local taxes (SALT, capped at $10,000), significant charitable contributions, or high unreimbursed medical expenses (above 7.5% of AGI).

Adjusting your W-4 for next year

The W-4 (Employee’s Withholding Certificate) controls how much your employer withholds each pay period. A large refund means you’re over-withholding — you could have had that money in your pocket all year. A balance due means you’re under-withholding — and amounts over $1,000 may trigger an IRS underpayment penalty.

• To reduce withholding (smaller refund, bigger paychecks): In Step 3 of the W-4, increase your dependent credits or other credits claimed.
• To increase withholding (avoid a balance due): Use Step 4c to enter an additional flat dollar amount per pay period.
• Life changes (marriage, new child, home purchase, second job) should trigger a W-4 update to keep withholding accurate.

What this calculator doesn’t include

• FICA payroll tax: Social Security (6.2% on first $176,100) and Medicare (1.45%, no cap). These appear on your W-2 but are separate from income tax.
• State and local income tax: Varies widely by state (0–13%); file a separate state return.
• Additional tax credits: EITC, education credits (AOTC, LLC), retirement savings credit, and others can further reduce your tax owed.
• Self-employment income: Adds self-employment tax (15.3%) and quarterly estimated payment obligations.
• Capital gains & qualified dividends: Taxed at preferential 0/15/20% rates, not ordinary brackets.
• AMT, NIIT, Additional Medicare Tax: Relevant for higher earners.