A property tax lien is a lien or claim for money due to a federal, state, or local government for unpaid and delinquent taxes. For example, the federal government may place a lien on a homeowner’s home or other real property for unpaid federal income taxes, and state and local governments (often counties) may place a lien on real property for unpaid income or property taxes.

The federal, state, or local government entity—also known as a taxing authority—may seek to recover payment for unpaid taxes by forcing the sale of the property on which the lien is placed in the foreclosure process—a process in which the validity of the lien and satisfaction (payment) for the lien is litigated or determined in court.

In Montana, a property tax lien represents a legal claim against a property by a governmental entity due to unpaid property taxes. When property taxes are delinquent, the county in which the property is located may place a lien on the property. This lien ensures that the tax authority gets first right to the property over other creditors. If the taxes remain unpaid, the county can initiate a foreclosure process to enforce the lien, which may result in the sale of the property at a tax lien sale or auction to satisfy the debt. The process for enforcing tax liens, including notification, redemption periods, and the conduct of tax sales, is governed by Montana state statutes. Additionally, for federal income tax delinquencies, the Internal Revenue Service (IRS) can place a federal tax lien on all of a taxpayer's property, including real estate. The federal tax lien process is governed by federal law, and the IRS has the authority to seize and sell real property to collect on the unpaid taxes after due process is provided to the taxpayer.