I generally forget to check my mileage in the car so I've been using mapquest or google maps for mileage. I mark my paperwork with the mileage. Then when I get paid, I input all the information, i.e., company, name of shop, fee, mileage and dollar amount for mileage. I have been deducting mileage for acting income for years and never put exact mileage, using just a guesimate, and never had a problem. I keep a running total. When I had a P.C., I used Microsoft Money to keep track of everything. It did all the math and it was easy to run reports. So, you could run reports for office supplies, phone calls, and mileage. I was told some time ago MS Money was no longer made because Microsoft conceded the accounting software to Quicken. I've never used Quicken, however, when I get a new laptop. I'll be using Quicken for my bookkeeping.