Mileage and Expense Log

Write it down the same week, or do not bother

A mileage record has two properties that determine whether it is worth anything: how detailed it is, and when it was written. Detail you can add later. Timing you cannot. A log built from a calendar six months after the fact is a reconstruction, and everybody who looks at it, including you, knows that.

The practical version for most people is a note on the phone the moment the engine goes off, three fields long: where, why, how far. Transcribing that into a proper sheet monthly takes ten minutes and produces something defensible. The failure mode is not sloppy handwriting; it is the missing weeks.

The rate field is empty on purpose

This page never supplies a rate. There are several in circulation at once, they apply to different situations, and they are revised. An employer reimbursing an employee may use one figure; a business deducting vehicle costs may face a different set of rules entirely, with a choice between a per-mile method and an actual-expense method that are not interchangeable year to year; driving for medical or charitable purposes sits under different provisions again. Which rate applies to you depends on who you are, who is paying, and what the driving was for.

So the field is yours to fill. Get the number from the party doing the reimbursing, from your written agreement with a client, or from your tax authority or CPA for anything with a tax consequence. Then the arithmetic on this page is just arithmetic.

The odometer cross-check

Reading the odometer at the start and end of a period costs nothing and catches the two errors that matter. If the log claims more distance than the odometer moved, something is duplicated or a distance is wrong, and that is worth finding before anyone else does. If the odometer moved much further than the log accounts for, the gap is personal driving, commuting, or trips that never got recorded.

A gap is normal. Most vehicles do business and personal driving in the same week. The point of measuring it is that a gap you can explain is unremarkable and a gap you cannot is the one that turns a five-minute conversation into an afternoon.

Rounding, and why the column adds up

Distance times rate rarely lands on a whole cent, so somewhere a rounding happens. Round each trip and add the column, and the column agrees with the total printed under it — which is what a reader checks first. Round once on the total distance instead, and the total is arguably more accurate but the individual line values no longer sum to it. On a log of a few dozen trips the two methods usually sit within a few cents of each other. Pick one, and pick the one your reimbursement system expects if it has an opinion.

Every dollar figure here is carried as an integer number of cents from the moment it is read out of the text box. Fractions of a cent never exist, so a total is never off by a stray hundredth that appears from nowhere in the last decimal place.

What this does not cover

Distance reimbursement is one line in the cost of running a vehicle. If what you actually want to know is what the vehicle costs you per mile all in, the car ownership cost calculator takes depreciation, insurance and maintenance rather than just fuel, and the fuel cost calculator handles a single trip. For splitting travel costs between people rather than claiming them back, the travel expense split does the settlement arithmetic, and the petty cash sheet handles the small cash spending that tends to travel alongside the driving.

Questions people ask