If you're self-employed, work-related driving is a legitimate tax write-off. You can deduct a share of the actual costs -- gas, oil, repairs -- or simply take the per-mile deduction, which is 55.5 cents per mile as of 2012. You can take the same deduction as an employee if your boss doesn't reimburse you for business travel.
If you drive for multiple employers, you don't have to take one deduction per job: You report all your mileage along with other unreimbursed expenses on Schedule A. Likewise, all your self-employment driving adds up to one single deduction on Schedule C, even if it's for multiple clients. If you have self-employment and employee mileage, you do have to submit both schedules. You should also keep records of which job or client you did the driving for, in case you're ever audited.
The daily commute to work is not deductible, even if you carry tools or important documents with you. Travel between different employers or job sites is different. When you drive from, say, your job at the office to your evening's work as a bartender, or between two different clients, those trips are deductible. If you add in other driving -- you go home between jobs, or stop off at your child's day-care -- you can only write off the mileage necessary for a straight trip between job sites.
Mileage Vs. Actual Expense
Taking the mileage deduction is simple. Track the number of miles you drive for work, multiply the total by the year's per-mile write-off and report it on the appropriate schedule. The actual-expense approach takes more work. Record your total mileage over the year, and what percentage is business travel. Then add up your car expenses and multiply by the business percentage. If 40 percent of your driving is deductible business travel, for instance, 40 percent of the total expense is a write-off.
If you're self-employed, you can write off all your business driving on Schedule C. Employees aren't so lucky, as you have to itemize. If you take the standard deduction, you lose any write-offs for job-related driving. Even if you do itemize, unreimbursed employee expenses are a "2 percent deduction." You have to add up all such deductions -- tax-preparation fees also fit in this category -- then subtract 2 percent of your adjusted gross income. You can only write off whatever is left.
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