Self Employment tax?

THere are two ways to deduct the use of your vehicle. You can do it by mileage (standard) or actual expenses for the use of the vehicle in the use of your business. Actual cost deducts any cost, gas, oil, license, registration. However, you will still need to know what miles have been in the service of the business and those that are personal. Generally, you will only need the proof if you are audited and bank statements can work for that. I would encourage you to make better records and to track your mileage. You may consider talking to a tax exert to better plan out how you will keep track of everything.

There are plenty of apps available to help you track your mileage. I highly recommend Mile IQ for this.

You need a mileage log regardless of whether you use standard mileage or actual expenses (gas, insurance, repairs, etc). Otherwise, how would you know what portion of the expenses are business vs. personal use? You can go back and reconstruct your records if possible. Otherwise, you might be able to keep a log going forward and then prorate for the 1st three months by taking an average.