Quick answerMontana sells tax lien certificates for unpaid property taxes. Lien buyers can earn 10% per year (5/6 of 1% per month) plus a 2% penalty on the delinquent amount (MCA 15-16-102). Redemption: 3 years from attachment of the tax lien, ending the first working day in August (MCA 15-18-111(1)); 2 years for property subdivided as a residential or commercial lot with delinquent special improvement district / rural SID assessments and no habitable dwelling or commercial structure on it (MCA 15-18-111(2)) Sales: No conventional auction in most counties: the county attaches the lien no later than the first working day in August (notice by the last Monday in June) and holds it; investors acquire it thereafter by assignment from the county treasurer (MCA 15-17-323) Governing law: Montana Code Annotated Title 15, Chapters 16-18 (MCA 15-16-102; 15-17-121 et seq., 15-17-323; 15-18-111; 15-18-211, 15-18-219 to 15-18-221).