Odometer Reading
Quick definition
Start-of-year and end-of-year vehicle odometer numbers. Required to verify total mileage on the tax return.
The IRS requires January 1 and December 31 odometer readings for every vehicle you claim mileage on. Schedule C Part IV asks you to break down total miles into business, commuting, and other.
Why both readings matter
Total annual miles (end odometer minus start odometer) is the denominator for business-use percentage calculations. Even if you use the standard rate (which does not require business-use percentage math), the IRS uses total miles to gut-check whether your claimed business miles are plausible.
How to capture them
A photo of the dashboard works. Many mileage apps prompt for an annual reading at year-end. A single screenshot dated to January 1 each year is the simplest evidence to keep.
Mid-year vehicle changes
If you place a new vehicle in service or stop using one mid-year, capture odometer readings at the date of change. You will report each vehicle separately on Schedule C Part IV.
Related terms
Business-Use Percentage
Business miles divided by total miles. Used to scale the actual-expenses deduction.
Schedule C
The federal form self-employed workers use to report business income and expenses, including the mileage deduction.
Logbook Method
Keeping a 12-week sample log to establish business-use percentage. Used by CRA in Canada and ATO in Australia.
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