Bookkeeping guide
Mobile mechanic / detailer tax bookkeeping: categories to review
Auto repair, detailing, tire and glass work. If you got a 1099 for this work, here are common categories and review questions; your facts and records determine what qualifies.
Worth knowing
These are common expenses people in this line of work may need to review. Anything marked in orange is an edge case worth raising with a preparer rather than assuming.
Parts you install for customers
Parts, tires, and glass you buy for a customer's job and bill to them are generally cost of goods sold rather than supplies or vehicle costs. Parts-store charges may first be suggested as vehicle expenses, so move customer-job parts to 'Parts & tires billed to customers'. Core-charge refunds generally reduce your parts cost; they are not new sales. PrivateBooks reports cost of goods sold only after you confirm no beginning or ending inventory and nothing taken for personal use, such as parts for your own car. If you keep parts or tires on hand at year-end, have a preparer calculate Schedule C Part III.
Part III no year-end stock
Driving to customers
Driving between customer jobs, and to a parts supplier during the workday, may be business mileage. Trips from home may be business or commuting depending on whether your home is your principal place of business and whether you have a regular work location. Keep a timely date, destination, purpose, and mileage log. The standard mileage rate generally must be chosen in the first year a vehicle is used for business. If you use it, don't also book gas, repairs, insurance, depreciation, or registration for that vehicle; business parking and tolls are tracked separately.
$0.70 / mile 2025 rate
Tools, scan tools & big equipment
Smaller hand tools, sockets, and shop consumables may be current Schedule C supplies when ordinary and necessary. Bigger items such as a scan tool, compressor, pressure-washer rig, or tool chest may need to be depreciated, or may qualify for Section 179 or the de minimis safe harbor election; decide with your preparer. Tool-truck payment plans can mix a tool's cost with finance charges that are treated differently, so keep every invoice and account statement.
at tax time big items
Garage liability & garagekeepers
Garage liability coverage generally protects you if your work causes injury or damage; garagekeepers coverage protects customers' vehicles in your care. The actual premium for a business policy may generally be an ordinary and necessary Schedule C insurance expense. Insurance on your own work vehicle is part of the standard mileage rate if you use that rate, so don't book it separately. Your own health insurance is not a Schedule C expense; any deduction for it is figured elsewhere on your return.
actual premium business use only
Detailing supplies & equipment fuel
Chemicals, pads, microfiber towels, and water you buy for jobs are generally Schedule C supplies when ordinary and necessary. Gas for a generator or pressure washer is equipment fuel, not vehicle fuel; keep those receipts apart from vehicle fill-ups, especially if you use the standard mileage rate. Split any receipt that mixes business supplies with personal shopping.
keep receipts split mixed buys
Sales tax on parts and services
Many states tax parts you sell, and some also tax repair labor or detailing; rules vary by state and locality. Whether collected tax is included in gross receipts (with the amount you remit deducted as a tax) or left out of both depends on how your state imposes it. Don't leave it out of income and also deduct it, and confirm the setup with your preparer.
varies by state confirm setup
Shop job vs. your own business
If you also work as an employee at a shop or dealership, tools and training you buy for that job are not Schedule C expenses, and unreimbursed employee expenses are generally not deductible on a 2025 federal return. Only costs of your own repair or detailing business belong here; a tool used for both generally needs a reasonable split. Contractor pay reported on a 1099-NEC generally belongs on Schedule C. If a shop that sets your hours and methods pays you as a contractor, ask a preparer whether you are really an employee.
W-2 vs 1099 separate the jobs
Common categories PrivateBooks suggests
Pick Mobile mechanic / detailer during guided setup and PrivateBooks shows these categories mapped to Schedule C lines for review — no chart of accounts to invent. The mapping does not establish eligibility, business-use share, or substantiation:
| Category | Schedule C line |
|---|---|
| Parts & tires billed to customers | Line 36 — Purchases |
| Tools, shop & detailing supplies | Line 22 — Supplies |
| Work vehicle (mileage or actual costs) | Line 9 — Car and truck expenses |
| Business parking & tolls | Line 9 — Car and truck expenses (business parking and tolls) |
| Shop or garage bay rent | Line 20b — Rent/lease (other property) |
| Garage & business liability insurance | Line 15 — Insurance (other than health) |
| Lead & booking platform fees | Line 10 — Commissions and fees |
| Card processing fees | Line 27b — Other (bank & merchant fees) |
| Advertising & online listings | Line 8 — Advertising |
| Repair info & shop software | Line 27b — Other (software & subscriptions) |
| ASE, EPA 609 & training courses | Line 27b — Other (education & training) |
| Business licenses & permits | Line 23 — Taxes and licenses |
| Used oil, tire & fluid disposal fees | Line 27b — Other expenses |
| Phone bill (work %) | Line 27b — Other (phone & internet) |
Merchants it recognises automatically
On top of the 584 built-in sorting rules, this pack adds rules for Alldata, Autogeek, Chemical Guys, Chemicalguys, Harbor Freight, Identifix, Mygrant Glass, Rockauto, Shopmonkey, Tekmetric, Tire Rack, Tirerack, Worldpac, Yourmechanic. A matching description gets a suggested bookkeeping category; anything uncertain goes to Review instead of being guessed at. Spot-check every suggestion: a merchant match is not proof of business use, eligibility, allocation, or substantiation.
Do you even have to file?
Net earnings from self-employment of $400 or more generally require Schedule SE, but other filing rules can apply below $400. Whether you received a 1099, also have W-2 wages, had withholding, or need estimated payments depends on the full return. Review the official Schedule SE instructions or ask a qualified preparer instead of treating this bookkeeping guide as a filing decision.
See an optional cash-reserve illustration →
Educational pointers, not tax advice. Tax rules change and your situation is specific — worth asking about at tax time. The free IRS-sponsored VITA program helps people under its income threshold at no cost.