The IRS says that research expenses, including travel costs, are a valid 2 percent deduction for professors. The research has to be related to teaching, lecturing or writing on subjects related to the professor's duties and her professional field. Professors can deduct research costs only if their research isn't bringing in any income beyond their salary. Publishing in a research journal that doesn't pay contributors would be an example.
If the professor does make a profit on her work -- a best-selling book rather than an academic article, say -- she may qualify as self-employed. Any self-employment income goes on Schedule C, along with related business expenses. The deduction for Schedule C expenses allows self-employed individuals to write off many more expenses than the itemized 2 percent deduction. If the IRS decides the professor isn't really self-employed, it may take her to tax court over the write-offs.
Other Work Expenses
If the professor joins any professional or educational group, or subscribes to professional journals, those expenses are a 2 percent deduction. She can write off unreimbursed travel expenses too, though not the cost of commuting to her job. Any professional courses are deductible. Work clothes are not deductible unless they are mandatory for the job and can't be worn away from work.