For a deduction, the tracking is the easy half. The log is the deduction.
A mileage tracking app for taxes is a different object from a general mileage tracking app. The general one answers how far you drove. This one has to produce something that stands up if anybody asks, and that is a log with four specific things recorded against every trip, written at the time rather than assembled in April from a calendar and a memory.
Automatic detection is genuinely useful and it is not the point. It produces trips. A trip becomes a deduction only once somebody has said what it was for, and that is the field every app makes optional and every examiner asks about.
See what a trip record has to showThe short version
Four elements per trip, recorded while you still remember the reason.
Amount, time, place and business purpose. That is the whole standard, and the last one is where homemade logs fall over, because a spreadsheet of distances is not a record of anything. An app that captures the first three automatically and prompts for the fourth in three words has done the job.
The second thing to get right is the rate, which is not a constant. It changes, it changed mid-year in 2026, and the correct rate is the one in force on the date of the trip. That makes dated trips the unit of storage rather than monthly totals.
What a trip record has to show
IRS Publication 463 sets the standard for car expenses. An adequate record has to establish the amount, the time, the place or business destination, and the business purpose of the travel, supported by documentary evidence, and it expects records to be timely kept rather than reconstructed later.
Timely kept is a design constraint
Read that phrase as a requirement about when, not what. A log written at the end of the quarter from bank statements and a diary is a reconstruction. The app's whole job is to make recording at the time cheaper than not recording, which usually means one prompt, on the phone, while the car is still parked.
Business purpose in three words
The field people leave blank. Make it required and make it fast: a list of recent purposes to tap, plus free text. Client name, site name, what the trip was for. Nobody writes a paragraph, and nobody needs to, but an empty field is the difference between a log and a list of drives.
Commuting is not a business trip
The most common error in homemade mileage records, and automatic detection makes it worse rather than better, because the daily drive to work is the most reliably detected trip you have. The app should treat the regular commute as a category it can recognise and exclude, not as something the user remembers to strike out.
Try it
A month of driving, split the way the rules split it
Miles are not miles. The app has to know which kind each trip was, and it has to know it at the time rather than at the end of the year.
471.2 claimable
At the 2026 business rate of 76 cents a mile. The 410 commuting miles are worth 311.6 on paper and nothing in practice, because commuting is not deductible.
The rate is data, not a constant
The IRS publishes a standard mileage rate, and it moves. For 2026 the business rate is 76 cents a mile from 1 July to 31 December, and was 72.5 cents a mile from 1 January to 30 June. In 2025 it was 70 cents for the full year. The charitable rate has sat at 14 cents throughout, because that one is fixed by statute rather than adjusted.
Two consequences follow, and both are cheap to build in and painful to retrofit. The rate has to be looked up by the date of the trip, so a year that contains a rate change produces the right figure without anyone intervening. And trips have to be stored as dated events rather than as a monthly total, because a total cannot be re-rated.
It is also worth keeping the rate table visible rather than buried. People do check, and an app that shows which rate it applied to which period is one nobody has to audit by hand.
Standard mileage or actual expenses, and why it matters early
There are two ways to claim car costs: a standard rate per mile, or the actual costs of running the vehicle apportioned to business use. They are alternatives, not a menu you pick from at the end, and the choice has consequences that reach back into what the app should have been recording all year.
The standard rate needs mileage and purpose. Actual expenses needs every running cost, receipts for them, and a defensible business use percentage, which still comes from mileage. So mileage is required either way, and an app built only for the standard rate quietly rules out the other method for anyone who used it.
The practical answer is to record mileage properly and let costs live in a business expense tracking app alongside it, rather than trying to be both. The rules on switching between methods are specific enough that this is a question for whoever prepares the return, not for an app to decide.
What automatic detection actually gives you
Automatic trip detection is worth having. It removes the failure where someone forgets to press start, which is most of them. It is not a substitute for the log, and selling it as one is how people end up with twelve months of unclassified drives.
Detection also costs battery, and the amount depends entirely on how it is done. Reacting to significant location changes is cheap. Sampling continuously is not, and an app that flattens a phone by four in the afternoon gets deleted regardless of how good the log is. It is worth understanding what the hardware will do before promising anything, which is covered in recording a trip.
The pattern that works is detect, then classify. The app notices a trip and asks one question later that day: business or personal, and what for. Two taps, batched, at a moment when the person is not driving. That is a log somebody will actually finish.
What each way of recording mileage leaves you with
| Option | Amount and date | Destination | Business purpose | Written at the time |
|---|---|---|---|---|
| Odometer readings in a notebook | Yes | if you wrote it | rarely | Yes |
| Spreadsheet at year end | Yes | from memory | from memory | No |
| Calendar plus a map lookup | estimated | Yes | inferred | No |
| Automatic tracking, unclassified | Yes | Yes | No | Yes |
| A mileage log app you build | Yes | Yes | Yes | Yes |
Building one around how you actually drive
Mileage apps are usually subscriptions priced per driver, and they are built around a generic idea of a business trip. Plenty of work does not look like that: a contractor with three sites in a day, a mobile therapist whose destinations are confidential, a family business where one vehicle is shared and the split matters more than the total.
Newly is an AI app builder. You describe the app you want, including the way your trips actually break down, and it builds and ships a real mobile app you own. Plans start at $25 a month, there is no free plan, and iOS builds ship through App Store Connect. It does not connect to bank or card feeds and it is not an accounting product, so it sits alongside whatever you already use for the return. It fits with the rest of your internal business apps rather than replacing them.
Nothing here is tax advice, and the rules on method, substantiation and what counts as business use have more detail than a page like this can carry. Build the record properly and let the person who prepares your return decide what to do with it.
Questions people ask about mileage logs for taxes
IRS Publication 463 requires an adequate record to establish the amount, the time, the place or business destination, and the business purpose of the travel, supported by documentary evidence. Distance alone is not a log. The business purpose is the element most homemade records leave out and the one that is asked about.
Describe the trips you actually need to prove
Write down what your driving looks like and what a purpose field would have to say, and build the log around that rather than around a tracker.
Start building