A tax deduction reduces your taxable income, which can lower the amount of federal income tax you owe. Depending on the type of deduction, it may reduce your income before or after your Adjusted Gross Income (AGI) is calculated.
In simple terms, deductions shrink the portion of your income that's subject to tax. The lower your taxable income, the lower your tax bill may be.
How Tax Deductions Work
The tax calculation process generally follows these steps:
Start with Gross Income
Gross income includes income from sources such as:
- Wages and salaries
- Self-employment income
- Interest and dividends
- Retirement income
- Rental income
- Other taxable income
Subtract Eligible Deductions
Some deductions reduce income before AGI is calculated, while others reduce income after AGI is determined.
Determine Taxable Income
After all eligible adjustments and deductions are applied, the remaining amount becomes taxable income. A lower taxable income generally results in less tax owed.
Types of Tax Deductions
Standard Deduction
The standard deduction is a fixed dollar amount based on filing status. Most taxpayers claim the standard deduction because it's simple and does not require documenting individual deductible expenses.
For the 2026 tax year, standard deduction amounts are adjusted annually for inflation. Tax software automatically applies the correct amount based on filing status and current IRS guidelines.
Benefits of the standard deduction include:
- Easy to claim
- No need to track deductible expenses throughout the year
- Often provides the largest deduction for many taxpayers
Itemized Deductions
Itemized deductions are based on specific qualifying expenses paid during the year.
Common itemized deductions include:
- Mortgage interest
- State and local taxes (SALT), subject to applicable limits
- Qualified medical and dental expenses that exceed the allowable AGI threshold
- Charitable contributions
- Certain casualty and theft losses when permitted by law
Tax software compares your total itemized deductions to your standard deduction and generally applies whichever option provides the greater tax benefit.
Above-the-Line Deductions
Above-the-line deductions, also known as adjustments to income, reduce your income before AGI is calculated.
These deductions can be valuable because they're generally available whether you claim the standard deduction or itemize.
Common examples include:
- Student loan interest deduction
- Educator expenses
- Self-employed health insurance deduction
- Deductible retirement plan contributions, such as Traditional IRA, SEP IRA, and SIMPLE IRA contributions
- Health Savings Account (HSA) contributions, when eligible
Because these deductions reduce AGI, they may also help taxpayers qualify for other tax benefits that have income limitations.
Tax Deduction Formula
Taxable Income = Gross Income − Adjustments to Income − Deductions
This simplified formula shows how deductions reduce the amount of income subject to federal income tax.
How a Tax Deduction Saves You Money
Here's a simple example:
- Gross income: $60,000
- Tax deduction: $10,000
Taxable income becomes:
$60,000 − $10,000 = $50,000
If the taxpayer is in the 22% federal tax bracket, the deduction could reduce taxes by approximately:
$10,000 × 22% = $2,200
In this example, the deduction lowers taxable income by $10,000 and reduces the tax bill by about $2,200.
The actual value of a deduction depends on factors such as filing status, tax bracket, and other items reported on the return.
Tax Deduction vs. Tax Credit
Although both deductions and credits can reduce taxes, they work differently.
| Feature | Tax Deduction | Tax Credit |
|---|---|---|
| Reduces | Taxable income | Tax liability directly |
| Value | Depends on tax bracket | Dollar-for-dollar reduction |
| Example | A $1,000 deduction may save a fraction of $1,000 in taxes | A $1,000 credit reduces taxes by $1,000 |
| Common Types | Standard, itemized, and above-the-line deductions | Refundable, nonrefundable, and partially refundable credits |
Generally, tax credits provide a larger direct tax benefit because they reduce the amount of tax owed rather than merely reducing taxable income.
Special Deductions Available to Certain Taxpayers
Some deductions are available only to taxpayers who meet specific requirements. Examples may include:
- Self-employed business deductions
- Retirement contribution deductions
- Health Savings Account deductions
- Certain education-related deductions
- Qualified business income deductions, when applicable
Eligibility requirements and income limits can vary, so it's important to review the rules for each deduction.
Why AGI Matters
Many tax benefits are tied to Adjusted Gross Income (AGI).
A lower AGI may help taxpayers:
- Qualify for certain tax credits
- Increase eligibility for deductions
- Lower the taxable portion of Social Security benefits
- Meet income requirements for education and retirement tax benefits
Because of this, above-the-line deductions can sometimes provide benefits beyond simply reducing taxable income.
Choosing Between the Standard Deduction and Itemizing
Most taxpayers either claim the standard deduction or itemize deductions, but not both.
As a general rule:
- Claim the standard deduction if it's greater than your itemized deductions.
- Itemize if your deductible expenses exceed the standard deduction amount.
Tax software typically performs this comparison automatically and selects the option that results in the greatest tax benefit.