Montana SB 528 — ADU Statewide By-Right (MT)
Tracked preemption from the Montana overlay bundle.
Overview
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Effective
2023-10-01
Sunset
—
Authority
state
Scope
state:MT
Other Montana preemptions
Montana SB 323 — Duplex By-Right in Cities >=5,000Montana SB 382 — Montana Land Use Planning ActMontana HB 819 — Minimum Lot Size Cap in Cities >=5,000Montana HB 337 — Parking Minimum Cap for Multifamily Near TransitMontana SB 245 — Density Restriction Preemption in Residential ZonesMontana Property Tax Mill Levy Cap
Trigger predicate
When this evaluates true for a parcel, the law's preempted fields take precedence over base zoning.
parcel.base_zone_category ∈ {res_sf, res_mf, res_th, mu}Preempted fields
4 fields on the base district schema are rewritten when the trigger fires.
| Field | Op | Value | Note |
|---|---|---|---|
base_districts[category=res_sf].allowed_uses | add | adu | |
base_districts[category=res_mf].allowed_uses | add | adu | |
review_type | waive_discretionary | — | |
parking_ratio_adu | waive | — |
Citation
Authority source
Montana SB 528 (2023) — codified at MCA Title 76, Chapter 2
§ SB 528 §1–5
Research notes
Requires all local governments to allow at least one ADU by-right on any residential lot statewide. Applies regardless of city population. Prohibits owner-occupancy requirements, minimum lot size requirements beyond what applies to the primary dwelling, and additional parking requirements.