Yes, and Publication 463 says so in one sentence: if you prepare a record on a computer, it is considered an adequate record. The interesting question is not the format. It is that the IRS asks for four things about every business drive, a GPS log captures three of them without you doing anything, and the fourth is the one that actually gets deductions disallowed. In 2026 there is also a second trap, because the rate changed in the middle of the year.
What the IRS actually asks for
The reference is Publication 463, Travel, Gift, and Car Expenses, chapter 5. Its Table 5-1 is a grid: expense types down the side, required elements across the top. The row for transportation, which is where car mileage lives, asks for four things.
| Element | What the publication requires for a car |
|---|---|
| Amount | The cost of the car and any improvements, the date you started using it for business, the mileage for each business use, and the total miles for the year |
| Time | The date of the use of the car |
| Place or Description | Your business destination |
| Business Purpose | The business purpose for the expense |
That is the whole specification. There is no required form, no approved app list, no mandated column order. The publication says you should keep the proof in "an account book, diary, log, statement of expense, trip sheets, or similar record," which is deliberately broad. A spiral notebook qualifies. So does a spreadsheet. So does an app.
It also removes the receipt problem for driving. Documentary evidence such as receipts and canceled checks is normally required, but the publication lists an explicit exception where you have a transportation expense for which a receipt is not readily available. Nobody issues you a receipt for driving 14 miles to a client.
A GPS log covers three of the four by itself
Map the four elements against what a recording app produces and the split is clean.
| Element | Automatic? | Why |
|---|---|---|
| Amount (mileage per use) | Yes | Distance is what the recorder measures, per trip |
| Time (date of use) | Yes | Every trip is timestamped at the moment it happens |
| Place (business destination) | Yes | The route ends somewhere, and the endpoint is recorded |
| Business purpose | No | No sensor can tell why you drove. This one is yours |
This is worth sitting with, because it inverts how people usually think about mileage tracking. The hard part is not the miles. Miles are a solved measurement problem, and they are the part a phone does better than you do. The hard part is the sentence explaining why the trip happened, and that is the part no tracker will ever fill in.
The element GPS cannot record
Publication 463 says you must generally provide a written statement of the business purpose of an expense. Then it softens, usefully: the degree of proof varies with the circumstances, and if the business purpose is clear from the surrounding circumstances, you do not need to give a written explanation.
Its own worked example is a sales representative calling on customers along an established route. That person does not have to write a purpose statement for each trip. They can satisfy the requirement by recording the length of the delivery route once, the date of each trip at or near the time of the trips, and the total miles driven during the tax year. The publication adds that the nature of your work, such as making deliveries, is itself circumstantial evidence that the car was used for business, and that delivery invoices establish when.
The practical reading: if your driving pattern is repetitive and self-explanatory, the surrounding circumstances do a lot of work for you and a note per trip is unnecessary. If your driving is varied, or the same road serves both business and personal trips, write the purpose down. A one-line note entered at the time costs seconds and is the difference between a log that stands and a log that becomes an argument.
2026 is the year an undated log breaks
Most years, business mileage has one rate and a log that only records totals can be patched at filing time. 2026 is not one of those years. The IRS set the rate at 72.5 cents in Notice 2026-10, then revised it upward mid-year, citing fuel price increases.
| 2026 period | Business | Medical / military moving | Charitable |
|---|---|---|---|
| January 1 – June 30 | 72.5 cents | 20.5 cents | 14 cents |
| July 1 – December 31 | 76 cents | 23.5 cents | 14 cents |
| 2025, for comparison | 70 cents, all year | 21 cents | 14 cents |
A single annual mileage total cannot be priced under this structure. You need to know which side of July 1 each mile fell on, and the only thing that tells you is a per-trip date.
The size of the problem is easy to see. Take 12,000 business miles, split evenly across the year:
- 6,000 miles × $0.725 = $4,350
- 6,000 miles × $0.76 = $4,560
- Correct deduction: $8,910
Apply 72.5 cents to the whole year and you claim $8,700, leaving $210 on the table. Apply 76 cents to the whole year and you claim $9,120, which is $210 you are not entitled to. Neither figure is defensible, and both come from the same missing thing: dates.
This is where an automatic log quietly wins. Timestamps are not a feature you have to remember to use. They are a side effect of the recording, and this year they carry real money.
"You can't deduct amounts that you approximate or estimate"
That sentence appears as a note in chapter 5, and it is the shortest statement of the rule that catches people. A figure like "about 900 miles a month, call it 11,000 for the year" is exactly what it prohibits, no matter how honest or how close to true it happens to be.
The related requirement is timeliness. The publication asks you to record the elements at or near the time of the expense or use, because a timely kept record has more value than a statement prepared later when there is generally a lack of accurate recall. Note the wording: the value of the record is the point, not a filing deadline.
It is not as strict as people fear. You do not need to write down every expense on the day it happens. If you maintain a log on a weekly basis that accounts for use during the week, that log is considered a timely kept record. A Sunday evening pass over the week's automatically recorded trips, adding purposes, satisfies this comfortably.
Full reconstruction after the fact is a different matter. The publication contemplates rebuilding records where they were destroyed by circumstances beyond your control, giving fire and flood as examples. That is a casualty provision, not a workflow.
There is a sampling rule, and it has a condition
You can keep an adequate record for parts of a tax year and use it to prove business use for the whole year. The condition is that you must demonstrate by other evidence that the periods covered are representative of use throughout the year.
The publication's example is a car used to visit clients, meet suppliers and deliver work, with family personal use as well. Keeping adequate records for the first week of each month showing 75 percent business use, backed by invoices and bills showing the same business continued in the later weeks, is sufficient.
Sampling is genuinely useful for stable, repetitive driving. It is a poor fit for work that comes in bursts, and the burden of showing representativeness sits with you. If your recorder runs continuously anyway, there is little reason to reach for it.
The number almost everyone forgets
Look again at the Amount row: the mileage for each business use, and the total miles for the year. Total miles means all of them, business and personal together.
The reason is arithmetic. Your business use percentage is business miles divided by total miles, and that percentage governs more than the mileage deduction. It limits depreciation, and it decides whether you clear the more-than-50-percent test that determines which depreciation method you are allowed to use at all. Without the denominator, the fraction does not exist.
A tracker that only records the trips you tag as business gives you the numerator and nothing else. Two odometer photographs, one on January 1 and one on December 31, close the gap in about ten seconds a year. It is the cheapest piece of record keeping available and the one most often skipped.
Where the odometer quietly works against you
If you build the log from dashboard odometer readings, there is a systematic error in it, and it runs in the direction that overstates your claim.
A car does not measure distance. It counts wheel rotations and multiplies by a tire circumference stored at the factory. Anything that makes the real rolling circumference smaller than that stored value makes the count run fast: tread wear over the life of the tire, a smaller replacement size, low pressure, a heavy load. Manufacturers also prefer the error to land high rather than low. The result is that most cars over-read by roughly 1 to 3 percent, which we cover in detail in is your odometer accurate.
Put numbers on it. Log 12,000 business miles from a dashboard that runs 2 percent high and you actually drove about 11,765. The 235 mile difference is worth roughly $179 of deduction at the second-half 2026 rate. At the 3 percent end of the band it is closer to $266. Nobody is auditing anyone over a 2 percent tire circumference. But if a return is examined, the figure you want to hand over is the one measured independently of the car, and that is the GPS figure. It is also the smaller one, which is the direction a tax authority prefers.
If you want your own number rather than the industry band, our speedometer and odometer accuracy test gives you the percentage in one long drive, and the GPS odometer is the second meter you need to run it.
Trips, round trips, and lunch
One small practical rule saves a lot of pointless entries. You can account for several uses of your car that form part of a single use, such as a round trip or uninterrupted business use, with a single record. And minimal personal use, such as a stop for lunch on the way between two business stops, is not an interruption of business use.
So a morning of four client visits ending back at the office is one record, not four, and the sandwich in the middle does not split it. The publication's own delivery example makes the same point: a route beginning and ending at the employer's premises, including a stop at the premises between two deliveries, can be accounted for with a single record of miles driven.
How long to keep it
Generally three years from the date you file the return on which the deduction is claimed, with an early-filed return treated as filed on the due date. If you claim depreciation instead of the standard mileage rate, you need records of business use for each year of the recovery period, which is longer.
Digital records make this trivial in a way paper never did. Export the completed year, store the file with that year's return, and the retention question answers itself.
The takeaway
A GPS log is an adequate record. The publication settles that explicitly by saying a record prepared on a computer counts. It also handles three of the four required elements better than a human with a notebook: distance per trip, date of use, and destination are captured automatically and without recall error.
What it cannot do is tell anyone why you drove. Business purpose is yours to supply, weekly is soon enough, and if your route is self-explanatory the circumstances may cover it. Add the two odometer photographs that give you total annual miles, use GPS distance rather than the dashboard so the figure is not quietly inflated, and in 2026 make sure every trip carries its date, because a mile in June and a mile in August are no longer worth the same amount.
If you want to see the underlying measurement for yourself, the browser GPS odometer records distance and duration with nothing to install, and the live speedometer shows the same GPS reading your car's dash is approximating.
This article describes what IRS Publication 463 says about substantiating car expenses. It is general information, not tax advice, and it does not cover state rules or your particular situation. For a decision that matters, talk to a tax professional.