What would make a checked bag fee deductible at all? Are you talking about personal travel or business travel?
If it's a personal trip, no part of the cost is deductible.
If it's a business trip, is it for your own business or self-employment, or are you an employee?
If you are an employee (you get a W-2), under current tax law none of your travel expense is deductible.
If you are traveling for your own business or self-employment, the amount that you actually pay can be deducted as a business expense. It doesn't matter whether it's for a seat or for a checked bag.
