Bookkeeping for Truckers & Owner-Operators: Cost Per Mile, Per Diem & IFTA

An owner-operator can gross $200,000 a year and still not know whether they're making money — because the profit hides inside fuel, maintenance, deadhead miles, and a tax picture most drivers never fully use. Trucking is a cost-per-mile business, and the drivers who win are the ones who actually know their number. This guide covers how owner-operator bookkeeping works: cost per mile, the per-diem deduction, IFTA fuel tax, reading your settlement statement, and the equipment write-offs that matter.

Why trucking bookkeeping is different

A trucking business generates a specific kind of complexity: income arrives on settlement statements from a carrier or broker (often with deductions already taken out), your single biggest cost is fuel bought across many states, you rack up tax obligations in every state you drive through, and your most valuable asset — the truck — depreciates and demands major repairs. Ordinary "money in, money out" bookkeeping misses all of it.

Cost per mile: the one number that runs the truck

If you learn one metric, make it cost per mile (CPM). It's your total operating cost divided by the miles you ran. Know your CPM and every load decision becomes math: a rate above your CPM makes money, a rate below it loses money, no matter how good the mileage looks.

Cost Per Mile = (Fixed Costs + Variable Costs) ÷ Total Miles Driven

The trap is deadhead and personal miles. If you divide costs only by loaded miles, your CPM looks better than reality — but you still paid for the empty miles. Track all miles, and track them by month, so the number stays honest.

Fixed vs. variable costs

• Fixed costs happen whether the truck rolls or not: truck payment, insurance, permits, ELD subscription, plates. Divided across fewer miles, they quietly raise your CPM in a slow month.
• Variable costs scale with miles: fuel (by far the largest), tires, maintenance and repairs, tolls, def, and per-load expenses. Fuel alone can be a third or more of every revenue dollar.

Clean books split these out so you can see which lever is moving — a repair spike, a fuel-price jump, or fixed costs eating you alive on low miles.

The per-diem deduction (don't leave it on the table)

Drivers subject to DOT hours-of-service rules can claim a special per-diem deduction for meals and incidental expenses on nights away from home — and unlike most business meals, the transportation-worker per diem is 80% deductible, not 50%. The IRS sets a flat daily rate (around $80 per full day under the special transportation-industry rate for 2025 — confirm the current figure), so you don't need meal receipts, just a log of days on the road. Over a year of overnights, this is one of the largest deductions an owner-operator has, and it's routinely missed or underclaimed.

IFTA: the fuel tax you file every quarter

If you operate across state lines in a qualifying vehicle, you file IFTA (International Fuel Tax Agreement) returns quarterly. IFTA reconciles the fuel tax you paid at the pump in each state against the miles you actually drove in each state, so the tax lands where the driving happened. That means you have to track miles by state and fuel purchases by state all quarter — not fun to reconstruct at the deadline, easy if your bookkeeping captures it as you go. Miss a quarter or get it wrong and you're looking at penalties and interest.

Reading your settlement statement

Your income shows up on settlement statements, and they're rarely just "revenue." A carrier or factoring company may net out fuel advances, insurance, trailer rent, escrow, ELD fees, or a factoring cut before you ever see the money. If you only book the net deposit, your revenue and your expenses are both understated and your CPM is wrong. Good bookkeeping records the gross settlement and each deduction separately, so your P&L shows what you really earned and what it really cost.

Your equipment: depreciation and Section 179

The truck and trailer are major assets, and their cost is recovered through depreciation over time — but tax rules like Section 179 and bonus depreciation often let you accelerate a big chunk into the year you buy. That's a significant tax lever, and it interacts with financing, so it's worth coordinating your bookkeeping with a tax pro before a major purchase. Your bookkeeper tracks the asset and its accumulated depreciation; your CPA picks the method.

Owner-operator, LLC, or S-corp?

Many owner-operators start as sole proprietors, then form an LLC and eventually consider an S-corp election as profit grows, to manage self-employment tax. There's no one answer — it depends on your net income and how you pay yourself — but clean books are the prerequisite for making that call intelligently, and for surviving the extra filings that come with each step.

How Tides handles trucker books

Owner-operator bookkeeping rewards someone who knows where the money actually hides. We set up your books to track cost per mile, split fixed and variable costs, record settlements at gross with every deduction itemized, capture the per-state fuel and mileage IFTA needs, and keep your per-diem and equipment records clean for tax time — then deliver monthly financials you can actually run the truck from. It's the kind of specialized work we do best; the whole picture is in our complete guide to small business bookkeeping, and if you're behind, catch-up bookkeeping gets you current before tax season.

Frequently asked questions