Definition: Nondeductible, also known as deductible or non-reimbursable, is a term commonly used in the United States and some other countries to denote an expense that cannot be deducted from income. This means that it does not count towards your taxable income. In the context of tax law, nondeductible expenses are those that are considered "non-taxable" by the IRS (Internal Revenue Service) and therefore cannot be claimed as deductions on your federal income taxes. Examples include charitable donations,