W-2 job plus gig driving: which miles count, and where the money goes on the return

Which trips count

Assume a full-time job and evening delivery work.

The pattern: the app being on when you start driving is what usually determines the answer, and going online in the car park at the day job rather than at the first restaurant is not a trick. It reflects when you actually started working, and the record should reflect it honestly.

The commuting rule, in detail. · The first and last trip of the day.

Where each piece lands on the return

W-2 wages flow through the usual employee path, with income tax, Social Security and Medicare already withheld.

Gig income and expenses go on Schedule C. Gross earnings from every platform, minus mileage, phone, supplies and other business expenses, produces net profit.

That net profit then does two things:

1. It is added to your other income for income tax.
2. It is subject to self-employment tax at 15.3 percent, with the deductible half of that adjusting income.

This is the part people are unprepared for. The gig profit is taxed twice over in a sense: income tax at your marginal rate, plus self-employment tax that your W-2 job's withholding does nothing about.

Every mile you record reduces both. Schedule C for gig drivers. · Why a deduction is not a refund.

The withholding move

Two ways to cover the gig tax.

Quarterly estimated payments. Four payments a year on the IRS schedule. Works, and it requires you to remember, and a missed quarter can produce an underpayment penalty even if you settle up in April. Quarterly estimated taxes.

Extra withholding on the W-4. Ask your employer to withhold an additional amount from each paycheck. Automatic, no dates to remember, and withholding is generally treated as paid evenly through the year regardless of when it was actually withheld, which is helpful if you started gig work mid-year.

For most people with a steady W-2 job, the W-4 is the better instrument. The number to withhold comes from your expected gig profit, not your gig gross, which is exactly why the mileage record matters before the year ends rather than after.

A worked year

Suppose $58,000 of W-2 wages and $14,000 of gross gig earnings on 11,000 business miles, split 4,800 in the first half of 2026 and 6,200 in the second.

• Mileage deduction: (4,800 × $0.725) + (6,200 × $0.76) = $3,480 + $4,712 = $8,192
• Other business expenses, say phone share and supplies: $600
• Net gig profit: $14,000 − $8,192 − $600 = $5,208

Self-employment tax applies to that $5,208, not to $14,000. Income tax applies to it, not to $14,000.

Without the mileage record, the same year reports $13,400 of profit and the tax on roughly $8,200 of it is money that did not need to be paid. That is the entire argument for tracking, and it does not require any interpretation of the rules to see.

The four numbers every gig driver should know. · The calculator.

Details that catch people

One vehicle, two uses, one annual total. You still need total miles for the year for the vehicle. Business use is a share of that total, and the share has to be plausible.

Do not deduct the day-job commute because you delivered afterwards. The morning drive is still commuting.

The standard rate versus actual expenses choice is per vehicle, not per job. Choose deliberately in the vehicle's first year of business use. Standard mileage versus actual expenses.

If your employer reimburses mileage, those miles are not also a deduction, and how the reimbursement was made affects how it is treated.

State rules differ. Some states still allow employee business expense deductions that the federal return does not. That is a state-specific question worth asking locally.

Questions and answers