Montana Building Permit Timelines & Delays
Montana's 2023 'Montana Miracle' is a bipartisan housing-preemption package that limits how much local governments can block new housing. The Montana Land Use Planning Act (SB 382) mandates growth planning and zoning reform for larger cities; SB 323 makes duplexes a permitted use in cities over 5,000; and SB 528 requires at least one accessory dwelling unit by right on single-family lots (codified at MCA 76-2-345).
Montana permitting, the figures
The key published figures for this jurisdiction — each cited to its official source.
What the data shows
Montana's 2023 package preempts local blocking of housing: SB 382 (the Land Use Planning Act) mandates growth planning, SB 323 makes duplexes a permitted use in cities over 5,000, and SB 528 requires at least one ADU by right on single-family lots (MCA 76-2-345).
After a 2025 district-court injunction against SB 382's public-participation limits, the Montana Supreme Court unanimously upheld SB 382, SB 323, and SB 528 on March 18, 2026, so the preemptions are now firmly in force (Montana Supreme Court, 2026).
The binding deadline on new subdivisions is the Montana Subdivision and Platting Act: a local government must act within 60 working days (80 for 50+ lots) of a sufficient application, or face a $50-per-lot, per-month penalty (MCA 76-3-604).
The 2025 session added follow-ups: HB 492 caps parking minimums (effective October 2026) and SB 532 extends ADU rights to counties, though a widely repeated '15-day structural review for ADUs' actually refers to a Department of Environmental Quality sanitation review under SB 532, not a structural one (Mont. HB 492 / SB 532, 2025).
Most delay accumulates before technical review
The data points to the same lever everywhere: most delay accumulates before technical review, in completeness and resubmittal cycles. Permittable's Permit Review Diagnostic checks your plans against applicable codes and common reviewer issues before you submit — so your package is more likely to clear on the first pass.
Montana permitting: FAQ
What is the 'Montana Miracle'?
It's the nickname for Montana's 2023 bipartisan housing-preemption package, which limits local governments' ability to block new housing. Key pieces: the Montana Land Use Planning Act (SB 382), by-right duplexes in cities over 5,000 (SB 323), and at least one ADU by right on single-family lots (SB 528, codified at MCA 76-2-345). The Montana Supreme Court upheld these laws in March 2026.
Are Montana's housing laws actually in effect?
Yes. A Gallatin County district court enjoined parts of SB 382 in 2025, but the Montana Supreme Court reversed that and unanimously upheld SB 382, SB 323, and SB 528 on March 18, 2026 (Montana Supreme Court, 2026). The preemptions are now firmly in force statewide.
What deadline applies to new subdivisions in Montana?
The Montana Subdivision and Platting Act sets the clock: a local government must approve, conditionally approve, or deny a subdivision within 60 working days of a sufficient application, 80 working days for 50 or more lots, or face a penalty of $50 per lot per month (MCA 76-3-604). This is the binding statutory deadline for new single-family subdivisions.
Is there a '15-day expedited structural review' for ADUs?
Not as usually described. The 15-day figure comes from SB 532 (2025) and refers to an expedited Department of Environmental Quality sanitation (water/septic) review for a county ADU added to a parcel with existing public water and wastewater capacity, codified at MCA 76-4-130, and set to sunset in 2029. It is an environmental review, not a structural plan review.
Sources
All figures on this page are drawn from Montana housing-preemption laws & the subdivision shot clock — Montana Legislature / Montana Supreme Court. Montana's 2023 'Montana Miracle' package (SB 382 (Land Use Planning Act), SB 323 (by-right duplexes), SB 528 (municipal ADUs, MCA 76-2-345), SB 245) upheld by the Montana Supreme Court in March 2026; the binding subdivision clock (MCA 76-3-604: 60 working days, $50/lot/month penalty); and 2025 follow-ups (SB 532 county ADUs, HB 492 parking, SB 133 impact-fee cap). mca.legmt.gov/bills/mca/title_0760/chapter_0030/part_0060/section_0040/0760-0030-0060-0040.html. Specific tables, reports, and pages are cited inline with each figure above.
These are statutory provisions and a court ruling, not measured outcomes: Montana publishes no statewide permit-approval-time data, so the figures are legal deadlines and mandates, not observed performance. The subdivision deadline (MCA 76-3-604) governs plats, a separate track from building-permit review. The 2025 follow-ups are frequently mischaracterized: HB 492 is parking reform, the impact-fee inflation cap is a different bill (SB 133), and the '15-day' ADU review is a DEQ sanitation review (SB 532), not a structural one.