If you use your personal car for business purposes, how can you write off your expenses? If you have another entity (S or C Corp or LLC) you are supposed to submit an expense report to the entity either for mileage (51 cents a mile) or your actual expenses for the mileage, which can be difficult to calculate. If the entity pays your auto bills for you, that is a personal payment, either a draw or a distribution or shareholder loan depending on the entity. It is better to submit and then reimburse rather than have the entity pay; just for clarity and having the documentation directly tie to a check.