Shoddy recordkeeping costs a tax preparer a large chunk of money. She can’t deduct her vehicle expenses, even though she used her personal car in her business. She claimed she drove 34,560 miles for business during the year, and she took the standard mileage allowance. But the mileage log that she kept had lots of holes, and the Tax Court didn’t find it reliable
The IRS requires “contemporaneous” record-keeping for mileage. That means a recording at or near the time of the trip. You can record the mileage at the time of the trip and enter the business purpose at the end of the week.
Brown, TC Oral Order