To calculate your net federal income tax, work through six steps in order: total your gross income, subtract above-the-line adjustments to reach your Adjusted Gross Income (AGI), subtract either the standard or itemized deduction to get taxable income, apply the marginal tax brackets, subtract any credits you qualify for, and then compare the result to what you have already paid through withholding or estimated payments. The result of that last comparison is your refund or your balance due. For the 2026 tax year, a single filer’s standard deduction alone shields the first $16,100 from tax, and a married couple filing jointly shields $32,200.
Step 1: Total Your Gross Income
Gross income is every dollar you received during the calendar year from every source the tax code doesn’t specifically exclude. That covers wages, tips, business profits, interest, dividends, capital gains, rental income, and retirement distributions.
For most people the source documents are a W-2 from each employer and 1099 forms for freelance pay, bank interest, dividends, or other non-wage income. Independent contractors receive Form 1099-NEC for payments of $600 or more. Add every figure together. That total is your gross income.
Accuracy at this step matters more than anywhere else. The IRS receives copies of every W-2 and 1099 issued in your name, and its matching program flags mismatches automatically. Underreporting triggers an accuracy-related penalty of 20% of the underpaid tax for negligence, rising to 75% if the IRS proves fraud. Forgetting a 1099 is the most common way filers end up owing penalties they didn’t expect.
Step 2: Subtract Adjustments to Get Your AGI
Before you decide between the standard deduction and itemizing, the tax code lets you reduce gross income by a specific set of expenses called adjustments. They apply whether or not you itemize, which is why practitioners call them above-the-line deductions. What remains after you subtract them is your Adjusted Gross Income.
The common adjustments include:
- Traditional IRA contributions of up to $7,500 for 2026, or $8,600 if you’re 50 or older. Deductibility depends on whether you or a spouse are covered by a workplace plan and on your income.
- Health Savings Account contributions of up to $4,400 for self-only coverage or $8,750 for family coverage in 2026, if you have a qualifying high-deductible health plan.
- Student loan interest of up to $2,500 per year, phasing out at higher incomes.
- Educator expenses of up to $300 for teachers and other eligible educators who buy classroom supplies out of pocket. Both spouses can claim $300 each if both qualify.
- Half of your self-employment tax, if you’re self-employed.
AGI is worth tracking carefully. It controls eligibility for dozens of other tax benefits, many of which phase out or disappear entirely above certain AGI thresholds.
Step 3: Subtract the Standard or Itemized Deduction
Once you have your AGI, subtract whichever is larger: the standard deduction, or the total of your itemized deductions. For 2026, the standard deduction amounts are:
- Single: $16,100
- Married filing jointly: $32,200
- Head of household: $24,150
- Married filing separately: $16,100
Roughly nine out of ten filers take the standard deduction because it’s simple and usually higher than what they could itemize. If your mortgage interest, state and local taxes (capped at $10,000), charitable contributions, and unreimbursed medical expenses above 7.5% of AGI together exceed your standard deduction, itemizing wins. Add up both and compare.
Whatever you subtract, the result is your taxable income. That is the figure that actually gets taxed. Keep supporting records for at least three years after filing.
Step 4: Apply the Marginal Tax Brackets
The federal income tax is progressive: different slices of your taxable income are taxed at increasing rates. Moving into a higher bracket does not raise the rate on the income already taxed at lower rates. Only the dollars above each threshold get taxed at the new rate.
For 2026, single filers face these brackets:
- 10% on taxable income up to $12,400
- 12% on income from $12,401 to $50,400
- 22% on income from $50,401 to $105,700
- 24% on income from $105,701 to $201,775
- 32% on income from $201,776 to $256,225
- 35% on income from $256,226 to $640,600
- 37% on income above $640,600
Married couples filing jointly have wider brackets. The 10% band covers the first $24,800, the 12% band runs to $100,800, and the 22% band extends to $211,400. The rates continue at the same percentages with roughly doubled thresholds through the 35% bracket.
Here is how the stair-step math works. A single filer with $75,000 in taxable income pays:
- 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 $24,600 (from $50,401 to $75,000) = $5,412
The tax before credits comes to $11,212. That is an effective rate of about 14.9%, even though the top bracket touched was 22%. This calculation is the core of the whole process.
Step 5: Subtract Your Tax Credits
Credits are more valuable than deductions because they reduce your actual tax bill dollar for dollar. A $1,000 deduction saves you $220 in the 22% bracket. A $1,000 credit saves you the full $1,000.
Credits come in two types. Nonrefundable credits can reduce your liability to zero but no further. Refundable credits can push past zero and produce a refund even if you owed nothing. Some credits are partially refundable.
The most widely claimed credits include:
- Child Tax Credit of up to $2,200 per qualifying child under 17 for 2026, with up to $1,700 refundable as the Additional Child Tax Credit. Income phase-outs apply at higher earnings.
- Earned Income Tax Credit, fully refundable, for low- and moderate-income workers. Maximum amounts for 2026 range from $664 for workers with no children to $8,231 for families with three or more qualifying children.
- Education credits: the American Opportunity Credit (up to $2,500 per student, partially refundable) and the Lifetime Learning Credit (up to $2,000 per return, nonrefundable).
Subtract every credit you qualify for from the tax figure you calculated in the bracket step. What remains is your net federal income tax liability. That is what the government says you owe for the year.
Step 6: Compare Your Liability to What You’ve Already Paid
Your net liability tells you the total, not whether you owe a check or get a refund. That comes from comparing it to what you paid in during the year.
If you’re an employee, your employer withheld federal income tax from every paycheck based on your Form W-4. The total withheld appears in Box 2 of your W-2. Self-employed taxpayers and those with significant non-wage income generally make quarterly estimated payments instead, which serve the same purpose.
The final step is simple subtraction. Take your net tax liability and subtract your total withholding plus any estimated payments. If you paid more than you owe, the difference is your refund. If you paid less, you owe the balance when you file. A large balance due can also carry an underpayment penalty.
If You’re Self-Employed, Add Self-Employment Tax
Freelance, side-business, and contract earnings carry an extra layer beyond income tax. Self-employed workers pay both the employee and employer shares of Social Security and Medicare, a combined 15.3% on net self-employment earnings. That is 12.4% for Social Security (on earnings up to the annual wage base) and 2.9% for Medicare (with no cap).
You calculate this on Schedule SE and report it on Form 1040. Half of the self-employment tax is deductible as an above-the-line adjustment, which lowers your AGI and therefore your income tax. The self-employment tax itself is separate from and in addition to income tax, so your total federal bill is higher than the bracket calculation alone suggests. Workers moving from a W-2 job to self-employment are often caught off guard, because an employer used to quietly pay half of these taxes.
Two Extra Taxes That Can Apply
Two additional federal taxes can push your bill above the standard calculation.
The Net Investment Income Tax adds 3.8% on investment income (interest, dividends, capital gains, rental income, and certain other passive income) when modified AGI exceeds $200,000 for single filers or $250,000 for joint filers. These thresholds are not indexed for inflation.
The Alternative Minimum Tax runs a parallel calculation that strips out many deductions and applies rates of 26% and 28% to a broader income base. For 2026, single filers are exempt on the first $90,100 of AMT income, and married couples filing jointly are exempt on the first $140,200. If the AMT figure is higher than your regular tax, you pay the higher amount. The AMT most often catches taxpayers who exercise incentive stock options, claim large state and local tax deductions, or have significant miscellaneous deductions.