How to Calculate Income Tax: A Simple Guide with Examples (2026)

The Short Answer

Income tax is calculated in five steps: start with your gross income, subtract adjustments to get adjusted gross income (AGI), subtract the standard or itemized deduction to get taxable income, apply the federal tax brackets progressively (only the slice of income inside each bracket is taxed at that rate), then subtract tax credits. Use our free Income Tax Calculator to run your exact numbers in seconds.

This guide walks through the 2026 federal numbers, a full bracket table, and two worked examples so you can see exactly how marginal and effective rates differ.

Step 1: Start With Gross Income

Gross income is everything you earned before anything was taken out: wages, salary, freelance and business income, interest, dividends, rental income, and unemployment compensation. Your W-2 Box 1 shows your wage total; freelancers add up 1099s plus any income without a form.

What gross income is not: the number your brackets apply to. Two subtractions come first, and they usually shrink it by a lot.

Step 2: Subtract Adjustments to Get AGI

"Above-the-line" adjustments reduce gross income to adjusted gross income (AGI). Common ones include qualifying traditional IRA contributions, HSA contributions, a portion of student loan interest, and the deductible half of self-employment tax. AGI matters because it is the base many credits, phaseouts, and the standard deduction build on.

Step 3: Subtract Deductions to Get Taxable Income

From AGI you subtract either the standard deduction or your itemized deductions (mortgage interest, charitable giving, state and local taxes up to the cap), whichever is larger. The 2026 standard deductions (announced by the IRS in October 2025) are:

Filing Status	2026 Standard Deduction
Single / Married Filing Separately	$16,100
Married Filing Jointly	$32,200
Head of Household	$24,150

These figures apply to the 2026 tax year (returns filed in 2027) and are adjusted annually for inflation. What remains after this subtraction is your taxable income — the only number the brackets touch.

Step 4: Apply the 2026 Federal Brackets Progressively

The seven 2026 rates are 10%, 12%, 22%, 24%, 32%, 35%, and 37%. The key word is progressive: each slice of taxable income is taxed at its own rate, so a raise never taxes your whole income at a higher rate.

Rate	Single	Married Filing Jointly
10%	$0 - $12,400	$0 - $24,800
12%	$12,401 - $50,400	$24,801 - $100,800
22%	$50,401 - $105,700	$100,801 - $211,400
24%	$105,701 - $201,775	$211,401 - $403,550
32%	$201,776 - $256,225	$403,551 - $512,450
35%	$256,226 - $640,600	$512,451 - $768,700
37%	Over $640,600	Over $768,700

Step 5: Subtract Tax Credits

Credits are the last and most powerful step: they reduce the tax itself, dollar for dollar, while deductions only reduce taxable income. Nonrefundable credits (like most education credits) can take your bill to zero but not below; refundable credits (like the earned income credit) can produce a refund. Don't confuse the two with deductions — a $1,000 credit beats a $1,000 deduction for almost everyone.

Worked Example 1: Single Filer, $80,000 Salary

No adjustments, standard deduction:

• Taxable income: $80,000 - $16,100 = $63,900
• 10% on the first $12,400 = $1,240
• 12% on the next $38,000 ($12,401-$50,400) = $4,560
• 22% on the remaining $13,500 ($50,401-$63,900) = $2,970
• Total federal income tax: $8,770

Marginal rate: 22% (the bracket the last dollar falls in). Effective rate: $8,770 / $80,000 = ~11% — half the marginal rate, because most of the income was taxed at 10% and 12%.

Worked Example 2: Married Filing Jointly, $150,000 Combined

No adjustments, standard deduction:

• Taxable income: $150,000 - $32,200 = $117,800
• 10% on the first $24,800 = $2,480
• 12% on the next $76,000 ($24,801-$100,800) = $9,120
• 22% on the remaining $17,000 ($100,801-$117,800) = $3,740
• Total federal income tax: $15,340

Marginal rate: 22%. Effective rate: ~10.2% of gross income.

Don't Forget Payroll Taxes and State Taxes

The examples above are federal income tax only. Employees also pay Social Security and Medicare payroll tax (7.65% combined for most employees; self-employed workers pay the full 15.3% self-employment tax, with Social Security applying up to an annual wage base of about $184,500 for 2026 and Medicare uncapped). Most states add their own income tax on top — a handful have none. When people say "my total tax burden," they usually mean all of these together, not just the federal income piece.

Three Mistakes People Make Every Year

• Thinking a raise taxed everything higher. Only the dollars inside the new bracket get the new rate — the rest keep their lower rates.
• Applying brackets to gross income. Forgetting the standard deduction inflates the estimate by thousands. A single filer never pays tax on the first $16,100 in 2026.
• Mixing up credits and deductions. A credit cuts your bill directly; a deduction only cuts the income the bill is computed from.

Want your number without the arithmetic? Our free Income Tax Calculator applies the 2026 brackets to your income and filing status instantly — no sign-up, no charge.

General information about US federal taxes, not tax advice. Bracket and deduction figures reflect the IRS 2026 announcement; confirm current guidance when filing.