Most ordinary operating costs of a business are 100% deductible, but the answer to how much of your business expenses you can write off depends on the category. Rent, wages, supplies, utilities, insurance, and professional fees generally come off your gross income in full. A short list of expenses — meals, gifts, vehicles, the home office, capital equipment, and pre-opening costs — comes with dollar caps, percentage limits, or usage rules that decide how much actually lands on your return. Federal tax only hits your net profit, so every dollar you legitimately deduct is a dollar the IRS never taxes.
The gate every expense has to pass through is Section 162 of the Internal Revenue Code: the cost must be “ordinary and necessary” for your trade or business.1Office of the Law Revision Counsel. 26 USC 162 – Trade or Business Expenses Ordinary means common and accepted in your industry. Necessary means helpful and appropriate, not indispensable. Personal, living, and family expenses are excluded, and mixing business into a personal trip doesn’t convert the personal portion into a deduction.
Expenses You Can Deduct in Full
The everyday cost of running a business is generally deductible dollar for dollar in the year you pay it. Rent for office space, a storefront, or equipment qualifies as long as you have no equity in the property.2Internal Revenue Service. FS-2007-14 – Deducting Rent and Lease Expenses Supplies, software subscriptions, advertising, shipping, and utility bills come off in full. So do employee salaries, wages, bonuses, commissions, and the employer’s share of payroll taxes.
Professional fees to attorneys, accountants, and consultants are deductible when they relate to business operations. Business insurance premiums — liability, property, workers’ compensation — are standard write-offs. Interest on business loans and credit lines is deductible, with tighter rules for very large businesses.
If a customer stiffs you on an invoice you already reported as income, you can claim it as a business bad debt in the year it becomes worthless, provided you’ve taken reasonable steps to collect.3Internal Revenue Service. Topic No. 453, Bad Debt Deduction Cash-basis taxpayers usually can’t write off unpaid service invoices, because the income was never reported to begin with.
Expenses With Caps and Limits
Business Meals: 50%
Meals with a clear business purpose — a client lunch, food for employees during a mandatory late shift, meals while traveling for work — are 50% deductible.4Office of the Law Revision Counsel. 26 USC 274 – Disallowance of Certain Entertainment, Etc., Expenses Transportation workers subject to Department of Transportation hours-of-service rules get 80%. Entertainment — concert tickets, golf, sporting events — is not deductible at all, even when business gets discussed over it.
Business Gifts: $25 per Recipient per Year
Gifts to clients or business contacts are capped at $25 per person per year, and that figure has not moved since 1962.4Office of the Law Revision Counsel. 26 USC 274 – Disallowance of Certain Entertainment, Etc., Expenses Branded promotional items costing $4 or less, like a logo pen or notepad, don’t count against the cap. Signs and display racks intended for a client’s premises are also excluded.
Vehicles: Standard Mileage or Actual Costs
For a car used in business, you pick one of two methods. The 2026 IRS standard mileage rate is 72.5 cents per business mile, and that single figure covers fuel, insurance, depreciation, and maintenance for gas, diesel, hybrid, and fully electric vehicles alike.5Internal Revenue Service. IRS Sets 2026 Business Standard Mileage Rate at 72.5 Cents Per Mile, Up 2.5 Cents
The actual-expense method lets you deduct the business-use percentage of your real costs: gas, oil, tires, insurance, lease payments, depreciation. Business-use percentage is business miles divided by total miles.6Internal Revenue Service. Topic No. 510, Business Use of Car Either way, commuting between home and your regular workplace is never deductible. Only trips to client sites, second work locations, and similar business destinations count.
Home Office: Regular Method or $1,500 Cap
If you use part of your home exclusively and regularly as your principal place of business, you can deduct a portion of your housing costs. A dedicated corner works; it doesn’t have to be a whole room, but you can’t use it for personal activities.7Internal Revenue Service. Topic No. 509, Business Use of Home The regular method allocates a percentage of mortgage interest or rent, utilities, insurance, and repairs based on the square footage of the office relative to the home. The simplified method is $5 per square foot up to 300 square feet, for a maximum of $1,500 per year.8Internal Revenue Service. Simplified Option for Home Office Deduction A sizable home office usually produces a bigger deduction under the regular method.
Two exceptions loosen the exclusive-use requirement: storing inventory or product samples when your home is your only business location, and running a daycare facility.9Internal Revenue Service. Publication 587 (2025), Business Use of Your Home
Equipment: Section 179 and Bonus Depreciation
Capital assets like machinery, vehicles, and furniture normally have to be depreciated over several years because their useful life exceeds one.10Office of the Law Revision Counsel. 26 USC 263 – Capital Expenditures Two provisions let you accelerate that.
Section 179 lets you deduct the full purchase price of qualifying equipment in the year you place it in service, up to $2,560,000 for 2026. That cap phases out dollar for dollar once total qualifying purchases exceed $4,090,000.11Internal Revenue Service. Revenue Procedure 2025-32 – Section 4.24, Election to Expense Certain Depreciable Assets SUVs over 6,000 pounds have a separate $32,000 Section 179 limit. The deduction also can’t exceed your taxable business income for the year, though the unused portion carries forward.
Bonus depreciation is a second lever with no dollar ceiling. It had been phasing down — 80% in 2023, 60% in 2024, 40% in 2025 — but the One Big Beautiful Bill Act restored 100% bonus depreciation for property acquired after January 19, 2025.12Internal Revenue Service. Notice 2026-11 – Interim Guidance on Additional First Year Depreciation Deduction For 2026 purchases you can stack the two, using Section 179 up to its limit and bonus depreciation on the rest, to write off the entire cost of qualifying equipment in year one.
Startup and Organizational Costs: $5,000 Now, the Rest Over 15 Years
Costs incurred before your business officially opens — market research, scouting locations, training, supplier travel — are startup costs. You can deduct up to $5,000 in the year the business begins operating. That $5,000 allowance shrinks dollar for dollar once total startup costs exceed $50,000, and disappears at $55,000.13Office of the Law Revision Counsel. 26 USC 195 – Start-Up Expenditures Whatever you can’t take immediately is amortized evenly over 180 months, starting the month you open.
Organizational costs — incorporation fees, drafting bylaws or an operating agreement, state filings — follow the same structure: a separate $5,000 immediate deduction with the same $50,000 phase-out, and 180-month amortization for the rest. The two buckets are tracked independently.
Write-Offs That Live Outside Schedule C
Some of the biggest reductions to a self-employed person’s tax bill don’t appear as business expenses at all. They come off elsewhere on the return and still cut the tax you owe.
Self-employed people can deduct 100% of the premiums they pay for health, dental, and vision insurance covering themselves, a spouse, dependents, and children under 27.14Office of the Law Revision Counsel. 26 USC 162 – Trade or Business Expenses – Section 162(l) It’s available to sole proprietors, partners, and S corporation shareholders who own more than 2%. Two limits: the deduction can’t exceed the net self-employment income of the business establishing the plan, and you lose it for any month you’re eligible for a subsidized health plan through a spouse’s employer or another job, even if you don’t enroll.15Internal Revenue Service. 2025 Instructions for Form 7206 – Self-Employed Health Insurance Deduction It’s an adjustment to gross income, so you get it whether or not you itemize.
Self-employment tax is 15.3% of net earnings, covering both the employer and employee halves of Social Security and Medicare. The tax code lets you deduct the employer-equivalent half, 7.65%, as an above-the-line adjustment to income.16Office of the Law Revision Counsel. 26 USC 164 – Taxes – Subsection (f) It doesn’t feel like a write-off because it sits on a separate form, but it directly reduces adjusted gross income.
Pass-through owners — sole proprietors, partners, S corporation shareholders, and LLC members taxed as any of those — may also deduct up to 20% of qualified business income under Section 199A. Originally scheduled to sunset after 2025, the deduction is now permanent. For 2026, income-based phase-outs begin around $197,300 for single filers and $394,600 for joint filers. Certain service businesses like law, accounting, and consulting lose access above the phase-out thresholds.
What Can Wipe Out Your Deductions
The Hobby Loss Rule
If the IRS decides the activity isn’t a real business, every expense deduction tied to it is disallowed. The safe harbor: if the activity shows a profit in at least three of the last five tax years, the IRS presumes it’s a business. For horse breeding, training, or racing, the threshold is two of the last seven.17Internal Revenue Service. FS-2008-23 – Is Your Hobby a For-Profit Endeavor? Failing the safe harbor isn’t automatic reclassification; the IRS also looks at whether you keep businesslike records, put in real time, depend on the income, and adjust methods to improve profitability. Consistent losses year after year with no realistic profit plan are the pattern that draws scrutiny.
Penalties for Overstating
Inflating deductions or claiming personal costs as business expenses costs more than repaying the tax. Negligence or careless disregard of the rules adds a penalty of 20% of the underpayment.18Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments Negligence here means failing to make a reasonable attempt to comply: sloppy records, ignoring well-known rules, claiming expenses without checking whether they qualify.
Fraud is far worse. If the IRS proves intentional inflation or fabrication, the penalty is 75% of the underpayment attributable to fraud.19Office of the Law Revision Counsel. 26 USC 6663 – Imposition of Fraud Penalty Once any part of the underpayment is proven fraudulent, the entire underpayment is presumed fraudulent unless you prove otherwise. Interest accrues on the tax and the penalty from the original due date.
Weak Documentation
No deduction survives an audit without records. The IRS expects receipts, invoices, canceled checks, and account statements identifying the payee, amount, date, and business purpose.20Internal Revenue Service. What Kind of Records Should I Keep For vehicles, keep a contemporaneous mileage log with date, destination, purpose, and miles. Reconstructing a log from memory months later is exactly what falls apart under examination. For meals, note date, location, attendees, and topic. For gifts, note recipient, cost, date, and business relationship.
Business tax records should generally be kept at least three years from the filing date. Employment tax records need four years. Claims involving worthless securities or bad debt deductions should be kept for seven.21Internal Revenue Service. Taking Care of Business: Recordkeeping for Small Businesses