A business writes off work-related expenses by deducting them from gross income when calculating taxable earnings, lowering the amount subject to federal and state taxes. These deductions must meet IRS criteria for being ordinary, necessary, and directly related to generating revenue.
Under Internal Revenue Code §162, the IRS allows businesses to deduct "ordinary and necessary" expenses incurred in carrying on a trade or business. An ordinary expense is common and accepted in the industry. A necessary expense is helpful and appropriate-not necessarily indispensable. The key is that the cost must be directly tied to business operations, not personal use.
For example, a freelance graphic designer who uses a $1,200 laptop exclusively for client projects may claim the full cost as a write-off. The IRS recognizes this as a legitimate business expense because the device supports core work activities. However, if the same laptop were used half for personal entertainment, only 50% of the cost qualifies for deduction.
Eligible work-related expenses fall into categories such as office supplies, software subscriptions, travel, equipment, and professional services. The IRS requires documentation-such as receipts, invoices, or bank statements-to verify both the existence and purpose of each expense.
Common examples include:
Not all costs qualify. Personal living expenses-like groceries, vacations, or clothing worn outside of work-are not deductible. Even if an item is used occasionally for business, the IRS disallows deductions unless the primary purpose is commercial.
Businesses use two main methods to write off assets: immediate expensing or depreciation. Immediate expensing applies to qualifying purchases under $1,220,000 in 2023 (Section 179 deduction). Depreciation spreads the cost over several years for longer-lived assets.
| Type | Eligibility | Example | Limitations |
|---|---|---|---|
| Immediate Expensing (Section 179) | Purchases under $1.22M | Printer costing $2,500 | Must be placed in service during the tax year |
| Depreciation (MACRS) | Long-term assets (over 1 year) | Delivery van bought for $35,000 | Spread over 5-year recovery period |
| Simplified Home Office | Primary residence used for business | 120 sq ft home office | $5/sq ft max = $600 deduction |
One often-missed rule: the IRS treats reimbursed expenses differently. If an employer provides a reimbursement plan, the employee cannot claim the same expense again. Conversely, if an employee pays out-of-pocket and later submits proof, the deduction stands-but only if the business maintains proper records.
Many entrepreneurs assume that any expense they incur while working counts as a write-off. This is false. The IRS distinguishes between business and personal use. For instance, a $400 gym membership used during lunch breaks may seem reasonable-but unless the business owns a fitness center or the member is a fitness trainer, it's not deductible.
Another frequent error involves mixed-use vehicles. A sole proprietor who drives 60% of their car's miles for client meetings can deduct 60% of fuel, insurance, and maintenance. But claiming 100% leads to audits and penalties. The IRS calculates mileage using logs, odometer readings, and trip purposes.
One non-obvious fact: the IRS considers "work" to mean activity that generates income. A consultant who attends a conference to network and pitch clients may deduct registration fees, travel, and lodging-but only if the primary intent was business development, not leisure. If the event includes significant social time, the deduction is reduced proportionally.
Consider Maya, a freelance web developer based in Austin. In 2023, she earned $84,000 in gross income. Her documented business expenses totaled $18,700:
Maya claimed the MacBook under Section 179, deducting the full $6,000 in 2023. She used the simplified method for her home office (150 sq ft × $5 = $750). After applying the 70% allocation for utilities and internet, her total allowable deductions came to $17,950.
Her taxable income became $84,000 − $17,950 = $66,050. Without the write-offs, her tax bill would have been higher by approximately $4,200, assuming a 24% marginal rate.
When I ran my own consulting firm, I learned the hard way that keeping a single spreadsheet for all transactions wasn't enough. I lost a $3,400 deduction because I couldn't prove a client meeting had occurred. Now I use digital tools to timestamp and categorize every receipt and interaction.
Writing off work is not the same as receiving a refund. Deductions reduce taxable income, which lowers the tax owed. They do not return money directly to the business. A $10,000 write-off reduces your tax bill by about $2,400 at a 24% rate-but you still paid the original $10,000.
Also, write-offs differ from credits. Credits reduce tax dollars owed dollar-for-dollar. Write-offs reduce taxable income. A $1,000 credit cuts your tax bill by $1,000. A $1,000 deduction cuts it by $240 (at 24%).
Some think that filing a business write-off automatically triggers an audit. That's untrue. Audits happen due to red flags-discrepancies, unusually high deductions, or missing documentation-not because someone claimed a write-off.