From pets to breast implants: These are the most unusual tax deductions the IRS has allowed. For an expense to be considered a tax deduction, it cannot be personal and must be the result of a financial investment of work, but there are exceptions.
In 1990, John and Joanna French won a case to deduct their private plane travel from their 1984 taxes. The same is true if someone goes to a gym to train because their doctor has told them to do so "to alleviate or prevent a physical or mental disability or illness"