What the statute does and does not do to your declaration

Read precisely, SB 532 changes the public side of the permission and leaves the private side alone. The county must permit; your covenant may still prohibit. The parallel city statute, § 76-2-345 (SB 528, Chapter 502 of the 2023 Laws, effective January 1, 2024), is built the same way.³

So an association whose declaration prohibits accessory dwelling units, second kitchens, or separate rental of part of a dwelling still has a covenant to enforce. What it has lost is the ability to point at the zoning code as backup — and with it, the argument that an owner's ADU is unlawful rather than merely prohibited by contract.

Two hard-edged provisions in subsection (5) are worth noting because they remove any waiting period: counties that had not adopted conforming regulations by the effective date must permit ADUs per the statute in the meantime, and non-conforming county regulations in effect on or after the effective date “are void.”

The unresolved question, stated plainly

Many older Montana declarations restrict lots to “single-family residential use” without defining the phrase and without mentioning ADUs at all. Whether such a covenant bars an accessory dwelling unit is unresolved in Montana as a matter of statutory interaction, and it is the question every board with a 1980s or 1990s declaration will eventually face.

What Montana does have is appellate authority on the private-covenant claim itself. In Myers v. Kleinhans, 2024 MT 208, the Supreme Court held that converting a garage into an ADU created “two separate single-family dwellings” on a lot whose covenant allowed only one, because the ADU was not “under the same roof” — and, separately, that renting it for profit was unambiguously a “commercial business” under a bare commercial-activity ban.² That decision turned on the words of a declaration that specified one dwelling per lot and defined “single family dwelling” as a building under one roof. A declaration lacking those specifics is in a different position.

What Montana no longer has is the district court declaration that the housing statutes cannot displace stricter covenants. It was vacated by the Supreme Court on March 17, 2026 as an advisory opinion. So an association enforcing an ADU restriction should argue from the statutory carve-out language quoted above and from its own document — not from that ruling.

What a board can expect, and what it can do

• Expect applications. Owners in counties with zoning can now get an ADU approved administratively, cheaply, and without a hearing. Many will assume approval settles the question.
• Establish whether your declaration actually prohibits one. This is the first question and it is often not the answer boards assume. A restriction on “single-family residential use” is not self-evidently a restriction on ADUs; a one-dwelling-per-lot clause is a stronger document.
• Check the architectural review timing. If the county can approve in weeks without a hearing, a review committee meeting quarterly is the bottleneck — and an owner who has already built is a harder problem than an owner who has applied.
• Remember the 2025 enforcement standard. Under House Bill 147, “enforcement action” on a covenant now means enforcement “equally and consistently … on all properties subject to the covenant over at least a 2-year period.” An association that has tolerated existing accessory units and then denies a new one is testing that definition.

One date in the statute

Section 4 of the act provides that “[sections 1(7) and 2] terminate September 30, 2029” — the expedited-sanitation-review pieces only. The ADU mandate itself carries no sunset.⁴