In Washington State,how much per mile can you write off on your taxes. IN my case I am drawing unemployment but have picked up about a half dozen jobs and have kept track of all my expenses.I try and stay honest as I can about everything.I went to Portland last week to do a job and I spent six days down there doing the job.I should be able to write off all my expenses from the trip....least I think so,but wasnt sure on the gas thing if it was the cost of the gasoiline,or do I deduct off so much per mile. Any advice would be greatly appreciated :)