Write-offs explained: why buying a G-Wagon doesn't make it free

By Tom, CPA · Updated October 27, 2026

Part of: Easy Tax Strategies

TL;DR: A write-off is a deduction that lowers taxable income, so it saves your marginal rate times the cost, not the whole cost. It must be an ordinary and necessary business expense. Heavy SUVs over 6,000 pounds get generous depreciation for 2026, but only for the business-use share, and the deduction can be recaptured later.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

There is a particular sentence that has launched a thousand truck purchases: "Don't worry, it's a write-off." It is usually said by someone who believes a write-off is a coupon from the government for 100% off. It is not. A write-off is a deduction, a deduction is a discount on taxable income, and the discount is worth only your tax rate.

This page explains what the term really means, how to value one, the rules a business expense has to pass, and the famous heavy vehicle rule, with 2026 figures from IRS Rev. Proc. 2025-32 as of October 2026. If you just want the list of refund myths, see tax refund hacks that don't work.

CPA Warning Label: Vehicles are a top audit topic. No mileage log, no deduction, and a big first-year write-off can come back as ordinary income when business use drops or you sell.

Deduction vs credit

Two very different things get called "write-offs."

• A deduction lowers the income that gets taxed. A $1,000 deduction in the 22% bracket cuts federal income tax by $220.
• A credit lowers the tax itself, dollar for dollar. A $1,000 credit cuts tax by $1,000. Some credits are refundable, meaning you can get money back even if you owe nothing.

Business expenses are deductions. They live on Schedule C (sole proprietors and single-member LLCs), Schedule E (rentals), or an entity return. For self-employed people, a business deduction also reduces self-employment tax, which is why a dollar of business expense is worth more to a freelancer than a dollar of an itemized deduction is to an employee.

And "write-off" is not "deduct this year" automatically. Many purchases, such as equipment, vehicles and buildings, are capitalized and depreciated over years. Special elections (section 179 and bonus depreciation) can speed that up, but speed is not the same as more.

Real value = rate × cost

The math fits on a sticky note: tax saved = cost × combined marginal rate. For a sole proprietor that combined rate can include:

• Federal income tax bracket (10% to 37% in 2026).
• Self-employment tax of 15.3% on 92.35% of net earnings up to the Social Security wage base ($184,500 for 2026; $192,300 for 2027 per SSA), then 2.9% Medicare above it, plus 0.9% Additional Medicare tax over $200,000 single or $250,000 joint.
• State income tax, if any.
• Minus the knock-on effects: lower profit also lowers your QBI deduction (up to 20% of qualified business income) and the half-of-SE-tax deduction.

These are rough, and the QBI interaction pulls them down a little. The point survives every rounding: you never get back more than about half. If you would not buy it at 55% off, don't buy it for the "write-off."

Business purpose

Section 162 allows deductions for expenses that are "ordinary and necessary" in carrying on a trade or business. Section 262 denies deductions for personal, living and family expenses. Between them sits every argument ever had about a laptop.

• Ordinary: common and accepted in your line of work. A camera for a photographer, yes. A boat for a bookkeeper, raised eyebrows.
• Necessary: helpful and appropriate, not indispensable. The bar is not high, but it is a bar.
• Mixed use: allocate. A phone used 60% for business is 60% deductible.
• You need a business: an activity engaged in for profit. Hobby expenses are not deductible at all for 2018 and later years (IRS hobby vs business guidance).
• Records: receipts, and for vehicles, travel and gifts, the stricter substantiation rules of section 274(d): amount, date, place and business purpose. Publication 463 covers what a log needs.

Meals with clients are generally 50% deductible. Entertainment, such as golf, concerts and the skybox, has been nondeductible since 2018.

Heavy vehicle rules

This is the "G-Wagon loophole." Here is what is real, as of October 2026.

• Luxury auto caps: section 280F limits annual depreciation on passenger autos. Vehicles with a gross vehicle weight rating above 6,000 pounds are generally outside those caps, which is why heavy SUVs and pickups get attention.
• Section 179 SUV cap: for 2026, the cost of a sport utility vehicle that can be expensed under section 179 is capped at $32,000 (Rev. Proc. 2025-32). The overall 179 limit is $2,560,000, phasing out above $4,090,000 of purchases.
• Bonus depreciation: the 2025 law restored 100% bonus depreciation, permanently, for qualified property acquired after January 19, 2025 (IRS guidance). That can cover the business-use share of a heavy vehicle beyond the 179 cap.
• More than 50% business use is required for 179 and bonus on listed property like vehicles. Drop to 50% or below in a later year and you recapture the excess depreciation as income.
• Only the business share counts. 70% business use means 70% of the cost is eligible. Commuting is personal.
• Sale: depreciation taken comes back as ordinary income when you sell (section 1245 recapture), up to the gain.

The alternative for most people is the standard mileage rate: 72.5 cents per mile for January to June 2026 and 76 cents from July 1, 2026 (IRS standard mileage rates page). Simple, audit-friendly, and no recapture surprise.

Example

Illustration: Dana, a self-employed consultant in the 32% bracket, buys a $110,000 SUV (GVWR 6,500 pounds) in 2026 and documents 60% business use with a mileage log.

1. Eligible business basis: $110,000 × 60% = $66,000.
2. With 100% bonus depreciation, Dana can deduct up to $66,000 in 2026 (combined with or instead of the $32,000 section 179 SUV amount).
3. Federal income tax saved at 32%: about $21,120. Dana is over the Social Security wage base, so SE tax savings are mostly the 2.9% Medicare piece: about $1,770 (on 92.35% of $66,000). Call it roughly $22,900 total before state tax and QBI effects.
4. Cash spent: $110,000. Net cost after year-one tax savings: about $87,100. The G-Wagon is about 21% off. Not free.
5. In 2028 Dana's business use falls to 40%. Excess depreciation over what straight-line would have allowed is recaptured as ordinary income that year.
6. If Dana sells in 2030 for $60,000, part of the gain on the business share is taxed as ordinary income under section 1245.

Meanwhile Dana's neighbor drove a paid-off sedan 8,000 business miles and deducted about $5,800 at the mileage rates without buying anything. Both are legal. Only one required a car loan.

Write-off claims that fail

• "My whole vacation is deductible because I checked email." Travel is deductible only when the trip is primarily for business. Side trips and family members' costs are personal (Publication 463).
• "My kids' clothes are a uniform." Clothing is deductible only if it is required for work and not suitable for everyday wear. Branded hoodies you wear to the grocery store do not qualify.
• "I can deduct my commute because I take calls in the car." Commuting between home and a regular workplace is personal no matter how many podcasts you record on the way.
• "Buying a house is a write-off." Mortgage interest and property taxes may be itemized deductions, subject to limits, and only help if itemizing beats the 2026 standard deduction of $16,100 single or $32,200 joint. The house itself is not deductible.
• "My W-2 job needs a home office." Employees generally can't deduct a home office on the federal return; the deduction is for self-employed people who meet the regular and exclusive use test (Publication 587).

When a write-off makes sense

• You were going to buy it anyway, for the business, and timing a purchase into a high-income year accelerates the deduction to when it's worth more.
• The asset earns its keep: it brings in more than it costs after tax.
• You can document it. Logs and receipts are the price of admission.

For more on business costs worth paying, see business credit cards for a side hustle, and the general myth-busting in dividend investing myths. The full lineup of simple moves is in easy tax strategies.