First, the honest framing
The IRS wants records made at or near the time you drove — contemporaneous records are the gold standard, and a reconstruction is always second-best. But second-best is a real category: the regulations explicitly allow you to substantiate an expense by reconstructing records with corroborating evidencewhen adequate records weren't kept. What separates an accepted reconstruction from a disallowed one is evidence. Every number must trace to something you can show.
And the thing never to do: sit down with a blank notebook and “remember” a year of driving. A fabricated log isn't a gray area — it's fraud, it looks exactly like what it is (uniform entries, round numbers, one pen), and it converts a lost deduction into penalties.
Your raw material
Most people can rebuild a surprisingly complete picture from:
- Odometer anchors. Oil changes, inspections, tire rotations, repair invoices — mechanics write the odometer on every ticket. Two readings bracket total miles for the period between them.
- Gig platform records. DoorDash/Uber/Instacart trip histories and annual summaries document dates worked and on-trip miles (remember they undercount working miles, but they prove the days and the floor).
- Calendar and appointments. Client meetings, showings, job sites — each entry is a documented trip with a date, destination, and purpose.
- Phone location history. Google Timeline or similar, if you had it on — imperfect, but strong corroboration.
- Receipts, invoices, and messages.A supply-store receipt proves you were there; the maps app tells you it's 18.4 miles round-trip.
The rebuild, step by step
- Bracket the year. Establish total miles from odometer anchors (or purchase /year-end readings). This is your ceiling; a reconstruction claiming more business miles than the car drove is dead on arrival.
- List documented trips. Go source by source — calendar, platform history, receipts — and write each trip with its date, destination, purpose, and the mileage from a maps lookup of the actual route.
- Fill recurring patterns carefully.If you drove the same route every Tuesday and can prove the pattern (standing appointment, work schedule, platform history), the IRS's own sampling principle helps: an adequate record for representative periods can substantiate the whole, when the pattern is demonstrated. Label these entries as what they are; don't disguise them as daily originals.
- Reconcile.Business + personal + commuting should plausibly sum to the bracketed total. If it doesn't, cut the claim, not the evidence.
- Write a cover memo.One page: what was reconstructed, when, from which sources. Transparency defuses the “March log in one pen” problem — you're not pretending it's contemporaneous.
Calibrate your expectations
A reconstruction supported like this generally holds up for the miles it documents. What you lose is the tail — the undocumented repositioning, the forgotten errands — which for a delivery driver can be thousands of miles. Reconstruct once, then never again: the entire problem is prevented by a log that takes ten seconds per trip, kept as you go.