How to Calculate Your Income Tax Return: AGI, Brackets, and Credits

To calculate your income tax return, you add up your total income, subtract adjustments to get your adjusted gross income, subtract either the standard deduction or your itemized deductions to reach taxable income, apply the federal tax brackets, subtract any credits you qualify for, and finally compare that number to what you already paid through withholding or estimated payments. Whatever is left is either a refund or a balance due. The math is layered but linear, and once you see where each figure comes from, the return stops feeling like a black box.

Step 1: Add Up Your Income

Start with everything you earned during the year. Federal law defines gross income broadly as income from all sources, so the list is long: wages, self-employment earnings, interest, dividends, capital gains, business profits, rental income, retirement distributions, and other taxable payments.1Office of the Law Revision Counsel. 26 USC 62 – Adjusted Gross Income Defined

Your source documents tell you most of the numbers. A W-2 from each employer shows wages paid and federal tax already withheld.2Internal Revenue Service. About Form W-2, Wage and Tax Statement3Internal Revenue Service. About Form 1099-NEC, Nonemployee Compensation4Internal Revenue Service. About Form 1099-INT, Interest Income5Internal Revenue Service. About Form 1099-DIV, Dividends and Distributions If you sold investments, a 1099-B reports the proceeds and cost basis. All of it lands on Form 1040.6Internal Revenue Service. About Form 1040, U.S. Individual Income Tax Return

Before you total anything, check that the name and Social Security number on every form match your Social Security card. A mismatch can delay processing or trigger manual review.7Internal Revenue Service. Instructions for Form 1040

Step 2: Subtract Adjustments to Find Your AGI

Adjusted gross income is the single most important number on your return. It sets your eligibility for many credits and deductions, and later steps reference it repeatedly.

From your total income, subtract a specific group of “above-the-line” adjustments. You can take these whether or not you later itemize:

Total income minus these adjustments equals your AGI, the figure at the bottom of page 1 of the 1040.

Step 3: Take the Standard Deduction or Itemize

Now reduce your AGI further using whichever deduction is larger: the standard deduction or your itemized total.11Internal Revenue Service. Deductions for Individuals: What They Mean and the Difference Between Standard and Itemized Deductions For most filers, the standard deduction is bigger.

The 2026 standard deduction amounts, reflecting inflation adjustments and changes made by the One, Big, Beautiful Bill Act, are:12Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026

  • Single or married filing separately: $16,100
  • Married filing jointly or qualifying surviving spouse: $32,200
  • Head of household: $24,150

Taxpayers who are 65 or older or legally blind get an additional amount on top of these figures. For 2025 that add-on was $1,600, or $2,000 if also unmarried.

Itemizing on Schedule A only beats the standard deduction if your qualifying expenses exceed the amount above. The main itemizable items are mortgage interest, state and local taxes, charitable donations, and unreimbursed medical expenses that exceed 7.5% of your AGI.13Internal Revenue Service. Tax Basics: Understanding the Difference Between Standard and Itemized Deductions Two limits shape the math for higher-income filers: the combined deduction for state and local income (or sales) taxes plus property taxes is capped at $40,400 for 2026, with a phasedown for modified AGI above $505,000, and interest on up to $750,000 of newer acquisition mortgage debt remains deductible.

AGI minus your chosen deduction equals your taxable income. That is the number the tax brackets actually apply to.

Step 4: Apply the Tax Brackets

Federal income tax is progressive. Different slices of your taxable income are taxed at increasing rates, so you never pay the top rate on every dollar. For 2026, the brackets for single filers are:

  • 10% on the first $12,400
  • 12% on $12,401 to $50,400
  • 22% on $50,401 to $105,700
  • 24% on $105,701 to $201,775
  • 32% on $201,776 to $256,225
  • 35% on $256,226 to $640,600
  • 37% on anything above $640,600

Married couples filing jointly get wider brackets. The 10% bracket covers the first $24,800, the 12% bracket runs to $100,800, and the schedule tops out at 37% on income above $768,700.12Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026

A Worked Example

Say you are a single filer with $60,000 in taxable income. The tax builds up layer by layer:

  • 10% on the first $12,400 = $1,240
  • 12% on the next $38,000 (from $12,401 to $50,400) = $4,560
  • 22% on the remaining $9,600 (from $50,401 to $60,000) = $2,112

Total federal income tax before credits: $7,912. That works out to about 13.2% of taxable income, even though you are “in the 22% bracket.” Your marginal rate is the rate on your last dollar. Your effective rate is what you actually pay overall, and it is always lower.14Internal Revenue Service. Federal Income Tax Rates and Brackets

Step 5: Subtract Your Credits

Credits reduce your tax bill dollar for dollar, not just the income being taxed. A $1,000 credit saves you $1,000 regardless of your bracket, which is why credits usually matter more than deductions of the same size.

Child Tax Credit

The Child Tax Credit provides up to $2,200 per qualifying child under age 17.15Office of the Law Revision Counsel. 26 USC 24 – Child Tax Credit If your tax liability is low or zero, a refundable portion (the Additional Child Tax Credit) can still put money in your pocket, up to $1,700 per child for 2025.16Internal Revenue Service. Child Tax Credit The credit phases out at higher incomes; married couples filing jointly well above $400,000 in AGI see a reduced amount.

Earned Income Tax Credit

The Earned Income Tax Credit targets low- and moderate-income workers and can be worth more than the Child Tax Credit for larger families. For 2025, the maximum ranged from $649 with no children to $8,046 with three or more qualifying children, with slightly higher 2026 amounts after inflation adjustments.17Internal Revenue Service. Earned Income and Earned Income Tax Credit (EITC) Tables The EITC is fully refundable, so it can generate a refund even if you owe no tax. It phases in as you earn income and phases out above thresholds that vary by filing status and family size.18Office of the Law Revision Counsel. 26 USC 32 – Earned Income

Other Credits Worth Checking

Education credits such as the American Opportunity Credit (up to $2,500 per student for the first four years of college) and the Lifetime Learning Credit apply if you or a dependent paid tuition. The Child and Dependent Care Credit offsets daycare or after-school costs. Energy-efficient home improvements and electric vehicle purchases may also qualify. Each has its own income limits and eligibility rules.

Subtract every credit you qualify for from the tax figure you calculated in Step 4. What remains is your final federal tax liability for the year.

Step 6: Compare Your Tax to What You Already Paid

This is the step that decides whether you get a refund or write a check. Look at Box 2 of your W-2 for the federal income tax your employer withheld during the year. If you made quarterly estimated tax payments (common for freelancers and self-employed workers), add those in. Then compare the total to your final tax liability from Step 5.

If payments and withholding exceed your tax, you overpaid and the IRS owes you a refund. If your tax is higher, you have a balance due. A large refund usually means your withholding was set too high, and a surprise balance means it was set too low. You can adjust for next year by submitting a new W-4 to your employer.

Don’t Forget State Income Tax

Your federal return is only part of the picture. Most states also impose an individual income tax, with top rates ranging from about 2.5% to over 13% depending on where you live, while roughly eight states have no individual income tax at all. Each taxing state has its own return, its own brackets, and its own deadline, and most states start their calculation from your federal AGI or taxable income. Finishing the federal return first makes the state return substantially easier.