If the employee is reimbursed for their business mileage, then the mileage rate includes depreciation.
If employees are reimbursed for actual costs, then depreciation is an actual car expense.
See in IRS Publication 463: ” If you don’t use the standard mileage rate, you may be able to deduct your actual car expenses. Actual car expenses include:
Depreciation, Licenses, Lease payments, Registration fees, Gas, Insurance, Repairs, Oil, Garage rent, Tires, Tolls, Parking fees ”
Learn More
(from page 22 at https://www.irs.gov/pub/irs-pdf/p463.pdf )
See pages 34 and 35 of IRS Publication 5137, at https://www.irs.gov/pub/irs-pdf/p5137.pdf