Figure B. When Are Transportation Expenses Deductible?

Summary: This illustration depicts the rules used to determine if transportation expenses are deductible.

Between home and regular or main job, Never deductible.
Between home and temporary work location, Deductible if you have a regular or main job at another location.
Between home and second job, Never deductible on a day off from regular or main job.
Between regular or main job and temporary work location, Always deductible.
Between regular or main job and second job, Always deductible.
Between temporary work location and second job, Always deductible.

The image then lists definitions for words used in the graphic:

Home: The place where you reside. Transportation expenses between your home and your main or regular place of work are personal commuting expenses.
Regular or main job: Your principal place of business. If you have more than one job, you must determine which one is your regular or main job. Consider the time you spend at each, the activity you have at each, and the income you earn at each.
Temporary work location: A place where your work assignment is realistically expected to last (and does in fact last) one year or less. Unless you have a regular place of business, you can only deduct your transportation expenses to a temporary work location outside your metropolitan area.
Second job: If you regularly work at two or more places in one day, whether or not for the same employer, you can deduct your transportation expenses of getting from one workplace to another. If you don’t go directly from your first job to your second job, you can only deduct the transportation expenses of going directly from your first job to your second job. You can’t deduct your transportation costs between your home and a second job on a day off from your main job.