One car, business and personal: figuring your business-use %
Almost every gig driver has exactly one vehicle doing double duty — grocery runs and school pickup on top of DoorDash and Uber. The IRS doesn't ask you to pick a lane. It asks you to split your total mileage into three buckets and report the business share.
Schedule C Part IV asks for three numbers: business miles, commuting miles, and other personal miles. Your business-use percentage is business miles divided by all three added together.
The three-way split, not two
It's tempting to think of mileage as just "business" versus "personal," but the IRS's own Schedule C instructions, Part IV split it three ways:
| Category | What it covers |
|---|---|
| Business miles | Driving performed for your gig work — deliveries, rides, and the trips covered here |
| Commuting miles | Home to your regular place of work and back — for most gig drivers, this doesn't really apply the way it does to an office job, but it matters if you have a separate fixed location you drive to first |
| Other personal miles | Everything else — errands, family driving, anything not business or commuting |
Commuting is its own category specifically because the IRS treats it as non-deductible personal driving, distinct from other personal use, not because it gets special treatment. The core rule: the trip between home and wherever you regularly work is personal, full stop, no matter how work-related the destination is once you get there.
The formula
Business-use percentage = business miles ÷ total miles (business + commuting + personal), for the vehicle, for the year. If you drove 18,000 total miles and 9,000 were business, your vehicle was 50% business-used. That percentage matters even if you use the standard mileage rate rather than actual expenses, because it's part of what the IRS Part IV disclosure asks for regardless of which method you choose.
Why this matters more with one shared vehicle than a dedicated one
A driver with a car used only for gig work has an easy business-use percentage: close to 100%. Nearly everyone else is somewhere well below that, and the percentage genuinely affects what you can claim if you ever switch to (or compare against) the actual-expense method, since actual expenses like depreciation, insurance, and repairs get pro-rated by business-use percentage — the standard mileage rate itself doesn't need the percentage to compute the deduction, only the Part IV disclosure does. See standard mileage vs. actual expenses for how the two methods compare.
The 2026 rate applies only to the business share
Whatever your business-use percentage works out to, the rate that applies to your business miles is the 2026 split-year rate: 72.5¢ per mile January 1–June 30, 76¢ from July 1 onward, from Notice 2026-10 (IR-2025-128) and Announcement 2026-11 (IRB 2026-29). Personal and commuting miles never get a rate applied to them — they simply don't factor into the deduction.
MileTruth. "One car, business and personal: figuring your business-use %." Baker Ventures LLC, September 8, 2026. https://miletruth.bakerventuresstudio.com/answers/vehicle-used-for-business-and-personal