The Mileage Log That Survives an IRS Audit

GigOdo Team · Published July 24, 2026 · Every figure sourced to the IRS unless noted

What the IRS actually requires in a mileage log

The IRS requires a record - an account book, diary, log, trip sheet, or app - showing the date, mileage, destination, and business purpose of every business use of your car, kept at or near the time you drive. That standard comes from IRS Publication 463, and it is the test an auditor applies.

For a gig driver, the mileage deduction is usually the biggest number on the return, and it sits in the strictest substantiation category in the tax code. This guide walks through what the rules say in the IRS's own words, what the Tax Court actually throws out, and the habits that make a log audit-proof. It anchors our whole Mileage & Records series. The habits below are far easier to keep with an automatic log running: here is how they apply to a DoorDash mileage tracker and to an Uber mileage tracker.

The four elements, straight from Publication 463

Table 5-1 of Publication 463 lists exactly what you must prove for car expenses: the date of each use of the car, the mileage for each business use, your business destination, and the business purpose. Around those trip entries, it also wants the car's cost, the date you started using it for business, and your total miles for the year.

In practice a compliant entry is short: "July 22 - 41 mi - Northside delivery zone - DoorDash deliveries." The destination can be an area rather than a street address, and the purpose can be brief when the work is obvious. The yearly totals come from two odometer readings - January 1 and December 31 - which also split your driving between business and personal use.

"Timely kept" beats "remembered"

Each element should be recorded at or near the time of the trip. Pub 463 is explicit about why: "A timely kept record has more value than a statement prepared later when there is generally a lack of accurate recall." You don't need same-day entries - a log maintained weekly is considered timely.

The weekly allowance comes straight from the regulation, 26 CFR 1.274-5T: a log maintained on a weekly basis that accounts for use during the week "shall be considered a record made at or near the time of such use." The failure mode the standard targets is the one most drivers fall into - a spreadsheet built from memory the week before filing. That is, by definition, a statement prepared later.

Why estimates are dead on arrival

Pub 463 is blunt: "You can't deduct amounts that you approximate or estimate." Vehicle use falls under Section 274(d) of the tax code, which requires every element - amount, time, place, and purpose - to be substantiated by adequate records or by sufficient corroborating evidence. A confident round number satisfies none of that.

This is also why the famous Cohan rule won't rescue you. Courts may estimate some ordinary business expenses when records are thin, but Congress overrode that for cars: The Tax Adviser confirms the Cohan rule cannot be applied to deductions under Section 274(d)'s heightened substantiation. The regulation adds that no deduction is allowed "on the basis of such approximations or unsupported testimony of the taxpayer."

What the Tax Court rejects - and what wins

Recent Tax Court decisions show a consistent pattern: vehicle deductions are denied when logs are missing or assembled after the fact, and they survive when electronic records exist. In Wolpert (T.C. Memo. 2022-70) and Eze (T.C. Memo. 2022-83), claimed vehicle expenses were disallowed for inadequate substantiation and a lack of contemporaneous records.

In another case covered by The Tax Adviser, the court noted it is simply "not permitted to estimate" deductions subject to Section 274(d) - no matter how plainly the taxpayer drove for work. The contrast case is Patitz (T.C. Memo. 2022-99), where the taxpayers won their mileage deduction because their electronic logbooks were accepted as sufficient contemporaneous records, per the Journal of Accountancy.

The lesson is mechanical, not moral. Judges don't weigh how honest you seem; they check whether dated, mile-by-mile records existed before the audit did.

Sampling: log part of the year, prove the rest

You don't necessarily have to log all 52 weeks at full detail. Pub 463's sampling rule says you can keep an adequate record for parts of the tax year and use it to prove business use for the entire year - if other evidence demonstrates the logged periods are representative of the whole year.

The IRS's own example: a taxpayer keeps adequate records the first week of each month showing 75% business use, and invoices show business continued at the same rate the rest of each month - that's sufficient for the year. A driver's parallel evidence is pay statements and order history showing similar weekly volume in the unlogged weeks. One honest caution: gig volume swings with seasons, so a sample that skips December's surge or January's slump is easy to challenge. A full-year automatic log never has that problem.

Gaps happen: the incomplete-records path

A missing element on some trips is not automatically fatal. Pub 463 says that if you don't have complete records, you can prove an element with your own written statement containing specific information plus "other supporting evidence that is sufficient to establish the element." It's a repair path for gaps - not a substitute for keeping the log.

Pub 463 even hands drivers a useful line: the nature of your work, "such as making deliveries, provides circumstantial evidence of the use of your car for business purposes," and invoices of deliveries establish when you used the car. If your problem is bigger than a few gaps - a whole untracked year - the fix is a full evidence-based rebuild, which we cover step by step in how to reconstruct a mileage log.

Parking, tolls, and the receipt question

Your miles themselves don't need receipts - the log is the substantiation, and the standard mileage rate replaces your operating costs. But business parking fees and tolls are "separately deductible, whether you use the standard mileage rate or actual expenses," per IRS Tax Topic 510 - so document those on top.

The receipt rules are gentler here than drivers fear: Pub 463 waives documentary evidence for expenses under $75 and for transportation expenses where a receipt "isn't readily available," which covers most cash tolls. A transponder statement captures the rest automatically. One trap worth knowing: parking you pay at your regular place of work is a nondeductible commuting expense - the deduction is for parking while working, like a paid garage during a downtown delivery.

The 2026 math: what a compliant log is worth

A compliant log is worth more in 2026 than ever, and it must be dated: business miles deduct at 72.5 cents each from January 1 through June 30 under IRS Notice 2026-10, and at 76 cents from July 1 through December 31 under Announcement 2026-11. Which half-year a mile falls in changes its value.

Assumes miles split evenly across the year. Sources: IRS Notice 2026-10; IRS Announcement 2026-11.

The mid-year split makes undated mileage totals worthless this year - a single annual number can't be priced. Dated entries assign every mile to its rate automatically. The full story of the 2026 rates, including what the rate covers and the depreciation component, is in our 2026 IRS mileage rate guide, and you can price your own miles with the mileage calculator.

Keep it three years - and make it automatic

Keep the log and its supporting receipts for at least three years from the date you file the return the deduction appears on, per IRS record-keeping guidance. The IRS gets six years when a return omits more than 25% of gross income. Keeping vehicle records longer than three years costs nothing and covers both windows.

Everything above - the four elements, timely kept, dated entries against a split rate - is exactly the problem an automatic tracker exists to solve. GigOdo detects your drives and records the date, miles, and route area as they happen, with a purpose field on every trip, so the timely-kept standard is met by construction. At filing time, the CPA-ready report pack exports the year as the dated, per-trip record an examiner asks for. The free tier has no trip cap, so the log runs all year regardless.

FAQ

Sources: IRS Publication 463; IRS Tax Topic 510; IRS newsroom on Notice 2026-10; Journal of Accountancy on Announcement 2026-11; 26 CFR 1.274-5T; The Tax Adviser, "Substantiation of Business Expenses" (2023); The Tax Adviser, "Individual Taxation: Recent Developments" (2016); Journal of Accountancy, "Digital Documentation" (2023); IRS, "How long should I keep records?". This article is general information, not tax advice.