What Is Deductible?

How this site works

Each page answers one specific question, then explains who it applies to, when it is deductible, when it is not, where it is generally reported, and what records matter.

Pages are reviewed against primary IRS sources such as forms, instructions, publications, revenue procedures, and IRS guidance. A page's review date is updated only after a substantive check or revision.

Scope: U.S. federal income tax rules. State rules can differ. Line references use the latest finalized IRS forms available, and pages note when a final 2026 form or instruction is not yet available.

Start here (60-second guide)

If you're trying to decide whether an expense is deductible, use the site like a checklist:

1. Pick the closest topic — mileage, meals, home office, software, insurance, rent, and so on.
2. Read the short answer — yes, no, or depends.
3. Check the conditions and exclusions that match your facts.
4. Separate business and personal use when an expense is mixed-use.
5. Check the reporting section for the relevant Schedule C or other form treatment.
6. Keep the records listed on the page to support the amount you claim.

For broader browsing, use the Expense Deductibility Guide and follow related lookups on individual pages.

What usually changes the answer

Many expenses are not a simple yes or no. Across the site, these factors commonly determine the result:

• Business purpose: What trade or business activity does the expense support?
• Business vs personal use: Mixed-use costs often require a reasonable allocation.
• Specific tax rule: Some categories have special limits, elections, capitalization rules, or eligibility tests.
• Method chosen: Mileage and home-office deductions can change depending on the method used.
• Reimbursements: You generally cannot deduct the same economic cost twice.
• Documentation: Receipts, logs, business-purpose notes, and allocation records can be as important as the category itself.

Recordkeeping checklist

Record requirements vary by expense, but this is a useful baseline:

• Receipt or invoice showing what you bought and when.
• Proof of payment such as a card statement, bank record, or payment confirmation.
• Business-purpose note explaining the project, client, trip, or activity involved.
• Allocation record for mixed business/personal use.
• Special logs when the category requires more detail — mileage, travel, meals, or home-office measurements.

Timely records are usually easier to support than records reconstructed much later. Check the individual expense page because documentation requirements differ by category.