Lots of drivers get to tax time with no mileage log, or one with big gaps. You can still deduct your business miles, but only the miles you can back up. A log rebuilt carefully from real records is far better than a round number, which the IRS can throw out completely.
What the IRS needs to see
Car expenses fall under strict record rules (section 274(d) of the tax code), so an estimate with nothing behind it isn't enough. For each business trip you need:
- The date.
- The miles driven.
- Where you went.
- The business purpose, such as "DoorDash deliveries" or "Uber rides".
You also need the total miles you drove the car that year, business and personal. A log written at the time carries the most weight. A log rebuilt later needs other records to support it.
Step 1: Work out your total miles for the year
Read your odometer now. For the reading on January 1, look for a dated odometer reading near it: an oil change or repair receipt, a state inspection, a car purchase or lease paper, or a photo of your dashboard. The difference, adjusted to the start and end of the year, is your total. Your business miles can't be more than this, and an auditor will check.
Step 2: Download every app's records
- Uber and Lyft: the yearly tax summary lists the miles you drove while online. The trip history shows each trip's date and time.
- DoorDash, Instacart, Amazon Flex and others: your earnings history shows the date and time of each dash, batch or block, and usually the stores, customers or stations you drove to. Use these to map each day's route.
The apps' figures leave out miles driven before you go online and after you go offline, such as the drive to your usual area and home again. Whether those count depends on your situation (see which miles count), so keep them on separate lines.
Step 3: Fill the gaps with other records
- Google Maps Timeline, if you had location history turned on. It is now stored on your phone rather than online.
- Gas receipts and bank or card statements, which show where you were on which day.
- Your calendar, messages and photos, for days you worked but have no app record.
Step 4: Rebuild it day by day
Make a spreadsheet with one row per working day or trip: the date, where you started and ended, the miles and the purpose. Measure each route on a map instead of guessing. Add up each month and check the year against your total from step 1.
Step 5: Be honest about what it is
- Note at the top that the log was rebuilt after the fact, and list the records you used.
- Only include miles your records support. A log that doesn't match the app records can put your whole mileage deduction at risk.
- Keep the log and the records behind it for at least three years after you file.
If the gaps are large or the miles are a big part of your deduction, a tax professional can help you decide what to claim.
Don't do this again next year
The simplest fix is a log that keeps itself. Gigstrak records trips in the background on Android, with the date and miles of each one. You mark each trip business or personal with a swipe and export an IRS-ready log at tax time. Get Gigstrak on Google Play.
Sources
IRS Publication 463 (chapter 5, recordkeeping) and section 274(d) of the Internal Revenue Code. This guide is general information, not tax advice.