Eligible Expenses tag is for questions dealing with expenses that qualify for a benefit or is allowed. Generally a tax question but could be for medical expenses, etc. Be sure to include additional tags to indicate what category of eligible expenses the question is about.
In the United States, only certain medical expenses are allowed to be deducted. For example cosmetic surgery is not eligible.
In the United States, travel by car from home to work is not considered a business expense for tax purposes, but driving from work to a seminar would be.