This base is very simple, because it makes good use of Airtable's linked record features. Add each person who might submit mileage to the "Drivers" table. Then in the "Trips" table, each time someone makes a trip, you'll pick the driver, miles driven, and the trip purpose. In the "Reimbursement Checks" table, record any time a driver is reimbursed for mileage.
This base is built to calculate how much each person is owed, taking into account their trips and how much you've reimbursed them already - find the calculations in the "Drivers" table. It assumes the current IRS mileage reimbursement rate of $0.56 per mile. To have drivers enter their own trips, use the "Mileage Form" view in the "Trips" table by copying the shareable link at the top.
Thanks for reading! Copy the base by clicking "Copy Base" in the bottom right corner of the embedded example, or visit the base in Airtable Universe here. If you found this useful, you might also like using the Business Expense Tracking base.