My wife teaches private piano lessons at our children's school. She is not employed by the school; payment is direct between student and my wife. Can she deduct mileage?

If you are self-employed and claim a dedicated home office—a space set aside exclusively for business—all the driving you do from your home to clients’ offices is deductible.

Per TurboTax article, Driving Down Taxes: Auto-Related Deductions: "If you don’t write off a home office," said Block, "your first and last trips of the day are considered non-deductible commuting." In other words, if you are a freelancer who regularly drives to different clients' offices in a day, the first trip out from home and the last drive back are not deductible. However, the distance driven between each client can be written off.

To enter vehicle expenses, like mileage, see Where do I enter my self-employment business expenses, like home office, vehicle mileage, and supplies?