The total amount of tax that an entity is legally obligated to pay to an authority as the result of the occurrence of a taxable event. Tax liability can be calculated by applying the appropriate tax rate to the taxable event's tax base. Taxable events include, but are not limited to, annual income, the sale of an asset, a fiscal year-end or an inheritance.

A tax liability is a legal claim on assets. Should an entity default on paying its taxes, the governing authority may foreclose on the delinquent account, or take out a lien or encumbrance on an asset.