Tax Liens are liens imposed on properties which has an unpaid tax debt in it. The Internal Revenue Service (IRS) is a government body who closely monitor the tax details of each and every property. If they found any properties with outstanding tax amounts, they will remind the taxpayer to settle the due within time by sending a series of notices. After the final federal notice, if the tax amounts still be the same, they will put a lien against the property. Once the lien is placed, the owner must pay the full tax amount with penalties and interest to the investor to get rid of the lien.
Source: tax lien