Montana Code Annotated — Title 15 (Taxation)
Mont. Code Ann. § 15-70-421 — Statute Of Limitations
15-70-421 . Statute of limitations. Except in the case of a fraudulent return or of neglect or refusal to make a return, every deficiency must be assessed within 3 years from the due date of the return or the date of filing the return, whichever period expires later.
Source: official text