How to calculate income tax?
Most taxpayers just want to know the bottom line: do I get a refund or do I owe money? In order to find that answer, take the total earnings and subtract the specific expenses the IRS lets taxpayers deduct. Once you have that "taxable" amount, the rates are applied and the result is compared against what was already taken out of the paychecks during the year.
What data should you collect?
Before running the numbers, the raw data should be gathered. You will need the filing status information as well as total income, pre-tax deductions, and a record of any taxes that were already paid.
- Filing status — Single, Married Filing Jointly, Head of Household
- Total income — Earnings from the job & side gigs, investments, and other sources
- Pre-tax deductions — items removed from the paycheck before tax, like 401(k) contributions or health insurance premiums or HSA funding
- Deduction strategy — whether you will take the standard deduction or itemize the expenses
- Tax credits — specific breaks expected to claim — like child tax credits
- Taxes paid — the total amount already sent to the IRS via paycheck withholding or estimated quarterly payments
How do you calculate income tax?
- Total your income — Combine the amounts from the W-2s & 1099s and other financial records
- Subtract adjustments — these are specific deductions that can be taken "above the line" to lower the gross income
- Subtract the deduction — apply either the standard deduction for the filing status or the total itemized expenses
- Apply the tax rates — the taxable income moves through the tax brackets, with each portion taxed at its specific rate
- Apply credits — subtract any tax credits you qualify for — they lower the bill dollar-for-dollar
- Compare to payments — check if the payroll withholding covered the final number — since withholding is just an estimate varyingg with your W-4, the final return will determine if you get a refund or owe a balance
Example calculation for 2026 — Washington, single filer
- Gross salary — $80,000
- Pre-tax 401(k) contribution — $5,000
- Adjusted gross income — $75,000
- Standard deduction (2026, single) — $16,100.
- Taxable income — $75,000 − $16,100 = $58,900
Federal income tax using 2026 single brackets:
- 10% of first $12,400 = $1,240
- 12% of next $38,000 ($12,400–$50,400) = $4,560
- 22% of next $8,500 ($50,400–$58,900) = $1,870
Estimated federal income tax: $7,670
Washington state income tax: $0
To complete this picture, subtract any credits & the federal withholding already taken from paychecks to get the refund / amount due.
Want a quick check with Clarity Tax Group before you file?
Reach out to Clarity Tax Group for a concrete estimate as well as a second set of professional eyes.