You may have read on this site about the mileage log and it's importance when you are taking the super good deduction or rather the mileage allowance from the IRS at tax time.
The Mileage Log is free to download here as a PDF.
You can download the Mileage Log here as an Excel file.
The IRS wants accurate information about every trip that you make and the miles driven for it.
There are also allowed some other items that you can list on the log as a deduction and you can read about them. Parking costs are also OK to list.
Gasoline is not. OK, so you have to know that the biggest deduction amount actually comes from the miles themselves.
The input of miles driven should be done when the miles are driven. Or, rather just after you make the trip so as to avoid any memory loss or confusion.
They have been known in a audit to refuse a later created log as being possibly false.
It could be accepted but with a decrease in your miles if so.
Some people use a computer software like Google maps to get the miles from the trip after they made the trip and didn't record it. It might be questioned by the IRS later though.
Start with your odometer reading on January 1 of the year being recorded. It is said that audits have increased in the area of mileage logs so do it properly. These deductions from mileage alone have reached about 15% of deductions recently.
The IRS prefers paper and ink logs rather than a computer logged and printed mileage numbers that can be easily faked.
They supposedly have to accept electronic though as stated in the IRS Publication 463.
Remember to write the miles in pen rather than in pencil to be taken more seriously.
The year 2016 had a business mileage rate that was different at $0.54 per mile.