• IRS Publication 535, Business Expenses, explains which business expenses are deductible, how to treat different types of costs (ordinary vs. necessary, capital vs. current), and the recordkeeping and accounting rules to support deductions.
– To be deductible an expense generally must be ordinary (common in your trade) and necessary (helpful or appropriate). Some items (capital expenditures, personal expenses, certain entertainment costs) are treated differently or disallowed.
– Your accounting method (cash vs. accrual) determines when you can take expense deductions. Capital costs are recovered by depreciation, amortization or expensing elections (e.g., Section 179).
– Accurate records, correct forms, and conservative allocations between business and personal use are essential to avoid penalties or audits.
What Publication 535 covers (overview)
– Publication 535 (IRS) is the IRS’s plain-language guide on business expenses: what’s deductible, what’s not, how to deduct expenses under cash or accrual accounting, and what records to keep.
– It clarifies differences between business expenses, cost of goods sold, capital expenditures, and personal expenses, and points readers to other related IRS guidance (for example, Publication 334 for Schedule C filers, Publication 463 for travel/car/meals, and Publication 946 for depreciation).
Most common deductible business expenses (high-level)
– Rent and utilities for business premises
– Employee wages, benefits and contract labor
– Professional and legal fees
– Advertising and marketing
– Insurance (business-related)
– Supplies and small equipment used in the business
– Interest on business loans
– Taxes paid because of the business
– Depreciation of business assets (capital expenses recovered over time)
(For detailed lists and limits by taxpayer type, see Publication 334 and Publication 463.)
How expenses must qualify for deduction
– Ordinary: The expense is common and accepted in your business or industry.
– Necessary: The expense is appropriate and helpful to your business (doesn’t require it be indispensable).
– Reasonable: Amounts must be reasonable in amount; excessive or inflated amounts can be disallowed.
– Proper allocation: If an expense has both personal and business use, you must divide it and deduct only the business portion.
New rules under the Tax Cuts and Jobs Act (summary)
– The Tax Cuts and Jobs Act (TCJA, 2017) changed various business deduction rules: for example, many entertainment expenses became nondeductible; limits on certain employee-paid expenses changed; lower corporate tax rate affected relative benefit for C corps; and new pass-through business deduction rules were added for certain owners (see IRS summaries for details).
– Because tax law changes periodically, always confirm current-year rules in the latest IRS publications and instructions.
What cannot be written off as a business expense (common examples)
– Personal living expenses (home mortgage, personal clothing, personal groceries)
– Commuting between home and a regular workplace (commuting costs)
– Entertainment expenses (generally nondeductible after TCJA)
– Political contributions and most lobbying expenditures
– Fines and penalties for violating the law
– Capital expenditures (purchase of long-lived assets) — these are not current deductions but are capitalized and recovered through depreciation, amortization, or Section 179 expensing rules
– Personal portion of mixed-use expenses (must apportion correctly)
Is it illegal to write off personal expenses as business expenses?
– Misclassifying personal expenses as business expenses on your tax return is illegal if done intentionally (it can lead to penalties, interest, and in severe cases criminal tax fraud charges).
– Even innocent mistakes can result in penalties, interest, and disallowed deductions. Always use conservative allocations and document the business purpose.
Practical, step-by-step guidance — how to claim business expense deductions safely
1. Determine your business entity and correct tax form
• Sole proprietors: Schedule C (Form 1040)
• Partnerships: Form 1065 and each partner gets Schedule K-1
• S corporations: Form 1120-S and shareholder K-1
• C corporations: Form 1120
• Different entities have different deduction rules and filing locations; Publication 334 helps sole proprietors.
2. Decide and document your accounting method
• Cash method: expenses deductible when paid.
• Accrual method: expenses deductible when all-events test is met and economic performance has occurred.
• Your method affects timing of deductions — Document and be consistent.
3. Classify each expense correctly
• Current business expense vs. cost of goods sold vs. capital expenditure.
• If asset is capital (long-lived), determine whether to depreciate/amortize or elect Section 179/bonus depreciation.
• Use Publication 946 and Form 4562 for depreciation and expensing rules.
4. Apply the “ordinary and necessary” test and check for special limits
• Confirm each item is ordinary and necessary for your trade.
• Check for special limitations (e.g., meals, entertainment, business interest limitations).
• For vehicle expenses, choose either actual expense method (keep receipts) or standard mileage method (keep mileage log and business purpose). Publication 463 explains vehicle and meal rules.
5. Keep contemporaneous, detailed records
• Save receipts, invoices, cancelled checks, bank/credit card statements.
• For travel/meal/entertainment and car use: record date, amount, place, business purpose, and business relationship of persons involved.
• Keep mileage logs showing date, mileage, business purpose, starting/ending odometer readings if using the standard mileage method.
• Retain records for at least the statute of limitations (typically 3 years, longer for significant understatements or fraud).
6. Allocate mixed-use costs
• If an expense is partially personal (e.g., cell phone, home office, vehicle), allocate the business portion using a reasonable method and document how you calculated it.
• For home office: meet “regular and exclusive use” and “principal place of business” tests (Publication 587 covers this in detail).
7. Use the correct forms and elections
• Report deductible expenses on the proper tax return and line items (e.g., Schedule C for sole proprietors).
• Make necessary elections timely (e.g., Section 179 election, accounting method changes require IRS approval in some cases).
8. Be conservative and consistent
• Don’t overstate the business purpose or amount. Conservative positions reduce audit risk.
• Be consistent year-to-year in your treatment of similar expenses, unless circumstances change.
9. If audited, be prepared to substantiate your deductions
• Provide receipts, logs, contracts, invoices, payroll records, and explanations as requested.
• If you discover an error before an audit, correct it on an amended return if appropriate.
Practical recordkeeping checklist (minimum)
– Receipts or invoices for every business purchase
– Bank and credit card statements
– Payroll records and Forms W-2/W-3, 1099-NEC for contractors
– Business mileage log with dates, purpose, and miles
– Travel itineraries, lodging receipts and meal receipts with business purpose
– Records showing business use percentage for mixed-use assets
– Depreciation schedules and asset purchase documents
Penalties and risks
– Accuracy-related penalties can apply for negligence or substantial understatement of tax.
– Intentional fraud can lead to civil fraud penalties and possible criminal prosecution.
– Interest accrues on unpaid taxes from the date they were due.
Related IRS publications and forms (core references)
– IRS Publication 535, Business Expenses (primary source for rules):
– IRS Publication 334, Tax Guide for Small Business (Schedule C filers):
– IRS Publication 463, Travel, Gift, and Car Expenses:
– IRS Publication 946, How to Depreciate Property:
– Form 4562 (Depreciation and Amortization):
– IRS summary of tax reform changes affecting businesses (TCJA):
– Investopedia overview of Publication 535
The bottom line
Publication 535 is the IRS’s practical guide to what business expenses you can deduct and how to handle them under different accounting methods. Follow the ordinary-and-necessary test, classify costs properly (current vs. capital), choose and stick to an accounting method, and keep clear, contemporaneous records. When in doubt about a complex issue (allocation, depreciation elections, treatment of special items), consult the relevant IRS publications or a qualified tax professional to reduce risk and ensure compliance.
– Create a one-page deduction checklist tailored to a sole proprietor in your industry.
– Draft sample language to document business purpose for travel or meals to use in your records.
– Summarize the specific 2023–2025 rules that affect meals, entertainment, and depreciation for your tax planning.