A tax write-off is an expense you subtract from your income to reduce the amount of income the IRS taxes

When you have a tax write-off (also called a deduction), you tell the IRS: "I earned this much money, but I spent this much on a legitimate expense, so tax me only on what's left." The IRS allows certain expenses to be subtracted from your income before calculating what you owe. The bigger your deductions, the smaller your taxable income, and the smaller your tax bill.

There are two ways to claim deductions: you can either add up all your individual expenses and claim the itemized deduction, or you can claim the standard deduction, which is a flat amount the IRS sets each year. Most people use the standard deduction because it's simpler and often larger than what they could itemize. But if you have large expenses—medical bills, mortgage interest, charitable donations, state taxes—itemizing might save you more money.

The key difference between a write-off and a tax credit: a write-off reduces your income, while a tax credit reduces your tax bill dollar-for-dollar. A $1,000 deduction might save you $200 or $300 in taxes depending on your tax bracket. A $1,000 credit saves you exactly $1,000. Credits are usually more valuable, but far fewer exist.

Key Takeaways

  • A tax write-off reduces your taxable income, which lowers the amount of tax you owe.
  • You can either claim the standard deduction (a fixed amount) or itemize your individual expenses—whichever is larger.
  • Common write-offs include mortgage interest, charitable donations, medical expenses, and state and local taxes, but only if you itemize.
  • Self-employed people can write off business expenses like home office costs, equipment, and supplies that employees cannot.
  • The value of a write-off depends on your tax bracket: someone in the 24% bracket saves $240 per $1,000 deducted, while someone in the 12% bracket saves $120.

Standard deduction versus itemizing: which saves you more

The standard deduction is a fixed dollar amount that changes each year and depends on your filing status. For 2024, the standard deduction is $14,600 for single filers, $29,200 for married filing jointly, and $21,900 for head of household. You straightforward subtract this amount from your income, no questions asked, no receipts needed.

If you itemize, you add up all your may be able to access expenses and subtract that total instead. You can only itemize if your total deductions exceed the standard deduction for your filing status. Itemizing requires keeping receipts and filing Schedule A with your tax return. The IRS may ask you to prove your deductions, so you need to keep records for at least three years.

The choice is straightforward: calculate both numbers and use whichever is larger. If your itemized deductions total $18,000 and you're single, itemize (since $18,000 is more than the $14,600 standard deduction). If they total $12,000, use the standard deduction instead. You cannot claim both.

Common expenses you can write off if you itemize

Mortgage interest and property taxes are the largest deductions for most homeowners. You can write off the interest portion of your mortgage payment (not the principal), plus state and local property taxes. However, the total of all state and local taxes (property tax, income tax, and sales tax combined) is capped at $10,000 per year.

Charitable donations to may have access to organizations—nonprofits, religious institutions, schools—are deductible. You need a receipt or written acknowledgment from the charity. Donations of goods (clothing, furniture) are deductible at fair market value, but you need a detailed list and photos for items worth more than $500 each.

Medical and dental expenses are deductible, but only the amount that exceeds 7.5% of your adjusted gross income (AGI). If your AGI is $60,000, you can only deduct medical expenses above $4,500. This threshold is high enough that most people don't benefit unless they had a major medical event.

State and local income taxes (or sales tax, if you choose) are deductible up to the $10,000 cap mentioned above. You cannot deduct federal income tax, Social Security tax, or Medicare tax.

Business write-offs for self-employed people

If you're self-employed, you can write off business expenses that reduce your profit. These deductions are taken on Schedule C, separate from itemized deductions, and they lower both your income tax and your self-employment tax. This makes business deductions especially valuable.

Common business write-offs include home office expenses (a portion of rent or mortgage, utilities, and insurance based on the square footage of your office), equipment and supplies, vehicle mileage (you can deduct either actual expenses or use the standard mileage rate, which was 67 cents per mile in 2024), professional services (accounting, legal), insurance, and education related to your business.

The rule is straightforward: the expense must be ordinary and necessary for your business. You cannot deduct personal expenses. If you use your car partly for business and partly for personal use, you can only deduct the business portion. Keep a mileage log and receipts for all business expenses.

Retirement account contributions as write-offs

Contributions to a traditional IRA or SEP-IRA (if self-employed) may be deductible in the year you make them, reducing your taxable income. A 401(k) contribution is deducted automatically from your paycheck before taxes are calculated, so it lowers your taxable income without any extra paperwork on your part.

The amount you can deduct depends on the account type and your income. For 2024, you can contribute up to $7,000 to a traditional IRA if you're under 50, or $8,000 if you're 50 or older. If you have a 401(k) through your employer, the limit is $23,500 (or $31,000 if you're 50 or older). Self-employed people can contribute to a SEP-IRA up to 25% of net self-employment income, with a maximum of $69,000.

The deduction is only available if you meet income limits. If you or your spouse has a workplace retirement plan, your IRA deduction phases out at higher incomes. Check the IRS rules for your specific situation, as the limits vary by filing status and whether you have access to an employer plan.

When bunching deductions makes sense

If your deductions are close to the standard deduction, you might benefit from bunching—timing expenses to exceed the standard deduction in one year and claim it, then use the standard deduction the next year. For example, if you're single and your normal deductions are $13,000 per year, you could make your charitable donation in December of one year and January of the next, pushing one year to $18,000 (itemize) and leaving the other at $8,000 (use standard deduction). Over two years, you deduct $26,000 instead of $29,200, but the timing matters.

Bunching works best with expenses you control the timing of: charitable donations, property tax payments, and medical procedures. It does not work with mortgage interest or property taxes that are fixed by your lender or local government. Talk to a tax professional before bunching, because the math depends on your tax bracket and whether you expect your income to change.

What you cannot write off

Personal expenses are never deductible. You cannot write off groceries, gas for commuting to work, car payments, rent (unless you're self-employed and using part of your home as an office), clothing, or entertainment. The IRS distinguishes between business expenses (deductible) and personal living expenses (not deductible).

You also cannot deduct federal income tax, Social Security tax, or Medicare tax. Some state and local taxes are deductible (income tax, property tax, sales tax), but federal taxes are not. Fines and penalties are never deductible, even if they're business-related. Lobbying expenses and political contributions are not deductible.

If you use something partly for business and partly for personal use, you can only deduct the business portion. For example, if you use your home office 20% of the time for business and 80% for personal use, you can only deduct 20% of the home office expenses.

Frequently Asked Questions

Should I itemize or take the standard deduction?

Calculate both. Add up all your potential itemized deductions (mortgage interest, property taxes, charitable donations, medical expenses). If that total is higher than the standard deduction for your filing status, itemize. If it's lower, use the standard deduction. Most people benefit from the standard deduction because it's simpler and often larger.

Can I deduct my home office if I work from home?

Only if you're self-employed or a business owner. Employees cannot deduct home office expenses. Self-employed people can deduct a portion of rent, mortgage interest, utilities, and insurance based on the square footage of the dedicated office space. You can use the simplified method (deduct $5 per square foot, up to 300 square feet) or calculate actual expenses.

Do I need receipts for all my deductions?

Yes, if you itemize. Keep receipts, bank statements, or written acknowledgments for at least three years. The IRS may ask you to prove your deductions. For charitable donations over $250, you need a written acknowledgment from the charity. For vehicle mileage, keep a log showing dates, destinations, and business purpose.

Can I deduct my student loan interest?

Yes, but it's not an itemized deduction. Student loan interest is deducted "above the line," meaning you can claim it even if you use the standard deduction. The maximum deduction is $2,500 per year. You do not need to itemize to claim it.

What's the difference between a deduction and a credit?

A deduction reduces your taxable income. A credit reduces your tax bill dollar-for-dollar. A $1,000 deduction saves you $120 to $370 depending on your tax bracket. A $1,000 credit saves you exactly $1,000. Credits are more valuable, but fewer exist. Common credits include the Earned Income Tax Credit, Child Tax Credit, and education credits.