If you use your car for work, this is what you can do with your expenses:
You can deduct your expenses using the standard mileage method or the actual expense method. If you use the standard mileage method, the standard amount includes allowances for gas, fuel, maintenance, repairs, and wear and tear. You can't deduct extra for repairs on top of the standard method. You need accurate records of your work-related mileage (date, miles, purpose) either using a paper log book or some kind of app.
If you use the actual expense method you deduct the total actual expenses, including fuel, repairs, maintenance, insurance and depreciation. You must have accurate records of ALL your mileage for the year (work and personal) plus accurate records of all your expenses. You deduct the percent of total expenses equal to the percent of work miles. The actual expense method is a lot more complicated and requires keeping more paperwork and proof, and the standard method usually works out better for most people.
If you are a W-2 employee, the deduction is an itemized deduction subject to the 2% rule so not everyone will actually benefit.
Also important for 2018:
If you are a W-2 employee, your ability to deduct work-related mileage ends on your 2017 tax return. The deduction was eliminated by the 2018 tax reform package. If you are self-employed, you can continue to deduct work mileage as an expense on schedule C.
