A future interest is vested when there is a person in being who would have a right, defeasible or indefeasible, to the immediate possession of the property upon the ceasing of the intermediate or precedent interest.
Mont. Code Ann. § 70-1-323
Future interest -- when vested
En
Official source: Montana Code Annotated (Montana Legislature). Reproduced from public-domain Montana statutes; confirm against the official source for the current text. Not legal advice.