A tax deduction is an expense or amount that you can subtract from your income before calculating how much tax you owe. Deductions reduce your taxable income, which lowers your tax bill. They’re not the same as tax credits — but understanding both is essential to making the most of every tax dollar.
Quick answer: what a tax deduction is
When the IRS calculates your income taxes, it doesn’t tax your entire gross income. It first allows certain deductions — legitimate expenses and contributions the tax code treats as reductions to your income. What’s left after deductions is your taxable income. Tax is calculated on that reduced number.
Example: if you earn $60,000 and take $16,100 in deductions, your taxable income is $43,900. You pay tax on $43,900, not $60,000.
Tax deduction vs. tax credit
This distinction is important:
- Tax deduction — reduces your taxable income. A $1,000 deduction saves you taxes equal to $1,000 multiplied by your marginal tax rate. If you’re in the 22% bracket, a $1,000 deduction saves $220 in taxes.
- Tax credit — reduces your tax bill directly, dollar for dollar. A $1,000 credit saves exactly $1,000 in taxes regardless of your tax bracket.
Credits are generally more valuable than deductions of the same dollar amount. Both reduce what you owe, but through different mechanisms.
The standard deduction vs. itemized deductions
Every taxpayer chooses between two approaches:
Standard deduction
A flat dollar amount the IRS allows every filer to subtract without having to document individual expenses. For 2026:
- Single filers: $16,100
- Married filing jointly: $32,200
- Head of household: $24,150
You take the standard deduction if it’s larger than the total of your itemized deductions. About 90% of filers use the standard deduction because the 2017 tax law nearly doubled it.
Itemized deductions
If your qualifying expenses add up to more than the standard deduction, you can itemize instead. Common itemized deductions include:
- Mortgage interest — interest paid on mortgages up to $750,000
- State and local taxes (SALT) — up to $40,400 in state income or property taxes in 2026 (less at incomes above $505,000)
- Charitable contributions — cash and non-cash donations to qualified organizations
- Medical expenses — the portion exceeding 7.5% of your adjusted gross income
Above-the-line deductions (adjustments)
Some deductions can be taken regardless of whether you itemize or take the standard deduction. These are called “above-the-line” deductions (because they appear above the adjusted gross income line on your tax return). Common ones include:
- Traditional IRA contributions — up to $7,500 per year in 2026 ($8,600 if 50+), if income limits allow
- Student loan interest — up to $2,500 per year if income is below certain thresholds
- Health Savings Account (HSA) contributions — if you have an HSA-eligible health plan
- Self-employment taxes — self-employed individuals can deduct half their self-employment tax
- Self-employed health insurance premiums
- Educator expenses — up to $300 for out-of-pocket classroom supply costs
- Alimony paid (for agreements before 2019)
Business deductions
Self-employed individuals and business owners can deduct ordinary and necessary business expenses, including home office costs, business equipment, professional services, advertising, business travel, and more. These reduce self-employment income, which in turn reduces both income tax and self-employment tax.
How deductions affect your tax bracket
The U.S. uses a progressive tax system with tax brackets — higher income is taxed at higher rates. Deductions don’t just reduce your tax; they can potentially move income out of a higher bracket. For example, a deduction that brings income from $95,000 to $89,000 moves some income out of the 22% bracket into the 12% bracket, saving money at the higher marginal rate.
Common mistakes
- Assuming every expense is deductible. Personal expenses — groceries, clothing, rent for your home, most commuting costs — are generally not deductible.
- Forgetting above-the-line deductions. Many people miss IRA and HSA deductions, which reduce taxable income without requiring itemization.
- Conflating deductions and credits. A $500 deduction is not the same as a $500 credit. Know which you have.
- Not tracking charitable contributions. Cash and non-cash donations throughout the year add up if you itemize — but you need documentation.
What to do next
Start by knowing which deduction method you’ll use. If your itemizable expenses (mortgage interest, state taxes, charitable giving) are clearly less than the standard deduction for your filing status, take the standard deduction and focus on above-the-line deductions like IRA contributions and HSA contributions — those reduce your taxable income no matter what.
Further Reading
This article is for general educational purposes only and does not constitute financial advice. Rules and rates change — verify specifics with your bank, employer, or a qualified advisor before acting.
