You can deduct your business mileage on your Schedule C for the months before your started operating your business as an S Corp.
For the S Corp to deduct business miles, it should be reimbursing you for the use of your personal vehicle. Otherwise, unreimbursed work-related expenses are generally not deductible on personal federal returns for tax years 2018-2025. You may still be able to take this deduction on your state return, however.
If your S Corp didn't reimburse you for your vehicle related expenses, those expenses would not be deductible.
For more information:
- Unreimbursed employee expenses
