Real estate offers many ways to invest, and one lesser-known method is tax lien investing . Unlike buying, flipping, or renting a property, tax lien investing focuses on purchasing the unpaid property tax debt of a homeowner. In some cases, if the property owner fails to pay, investors may even acquire ownership of the property. This guide explains the basics of tax liens, how the process works, and what to consider before investing. What Is a Tax Lien? A tax lien is a legal