What does the IRS actually require in a mileage log?

The IRS does not require an app

This is worth stating plainly, because a lot of mileage-app marketing implies otherwise. Publication 463 sets a standard for evidence, not for tooling. A paper notebook that records all four elements at the time of each trip is a valid record. An app is useful because it makes contemporaneous recording effortless and hard to forget — not because the IRS demands one.

"Timely kept" is the part people miss

Publication 463 asks for records made at or near the time of the expense, and treats a record maintained on a weekly basis as generally timely. The practical implication: a log written up in April for the previous calendar year is weaker evidence than one built as you drove. It is not automatically disallowed, but it carries less weight if questioned.

If you are in that position now, read what to do if you didn't track your miles — honestly, rather than optimistically.

In 2026, "date" carries extra weight

The date field has always been required. In 2026 it also determines which rate applies, because the business rate changed from 72.5¢ to 76¢ on July 1. A log with total miles but no dates cannot produce a correct 2026 deduction at all. See the 2026 two-rate explainer.

Where the miles end up on your return

For a sole proprietor, car and truck expenses go on Schedule C, Line 9. If you claim the standard mileage rate and are not otherwise required to file Form 4562, you complete Part IV of Schedule C, which asks for the date the vehicle was placed in service and a breakdown of business, commuting, and other miles. See the Schedule C instructions.

Note what Part IV implies: the IRS expects you to be able to separate business, commuting, and personal miles — not just report one total.