What can be a deduction for work expenses on an income tax return?

It is entirely situational and depends on many, many factors...like if your an employee or not (W-2 or 1099). What your employer provides and if you get reimbursed at all (and how) for it...many industries have fairly common guidelines that make certain things deductible, where others have others. Frankly, most "standard" employees, just going in and doing a job and getting paid don't have any unreimbursed work expenses that would qualify. The most common would be clothing, like a uniform, that is required and cannot be worn otherwise (a suit wouldn't qualify, nor would jeans...even if only used at work).