ADU Guide · Verified 2026
Building an ADU in New Mexico
New Mexico has no statewide ADU mandate. A bill that would have voided HOA restrictions on ADUs, House Bill 425, died in the House in 2023, and none of its successors have passed either.
Quick Facts
Statewide floors set by No statewide ADU law; HB 425 (2023) died in the House, no successor has passed. Your city may be more generous but cannot go below them.
The Three Types of ADU
A real bill that genuinely died
House Bill 425 (2023) would have allowed ADUs on single-family lots statewide and voided HOA restrictions blocking them, but the House postponed action on it indefinitely on February 14, 2023, a real, documented death, not an ambiguous stall. Some secondary sources have incorrectly described HB 425 as if it were enacted law; it was not.
A genuine two-layer question
Because New Mexico has no statute overriding private restrictions, whether an ADU is actually allowed on a specific property depends on two separate things: whether the local zoning code permits it, and whether the HOA declaration, if any, also permits it. Either one can block a project on its own.
A real cross-reference to the state shed rule
New Mexico's own residential building code exempts a one-story detached accessory structure under 120 square feet from needing a building permit at all, the same threshold used for garden sheds statewide, though this exemption is about structure size, not ADU legality specifically, and doesn't substitute for zoning approval of an actual dwelling unit.
What people get wrong
The most common mistake is citing HB 425 as if it created statewide ADU rights in New Mexico. It died in the House in 2023 and never became law, so the real answer always comes from the specific city or county's own zoning code, and separately, any applicable HOA declaration.
From Idea to Move-In: The Timeline
Who Administers It
Building It Yourself? Here's What You'll Need
Planning an ADU? Tools homeowners use in the design and layout phase:
As an Amazon Associate, we earn from qualifying purchases.
Check Your Local Rules
Your city may allow more than the state floor
State law sets the minimum; many New Mexico cities and counties are more generous. Browse the full directory of 33 counties and every city in New Mexico for local rules, fees, and building department contact details.
Browse the full New Mexico directory →Not sure if your project needs a building permit, a zoning approval, or both? See our guide to building permits vs. zoning approval.
Official Sources
ADU law changes frequently and local ordinances add detail. This guide is general information, not legal advice, always confirm with your local building department. Reviewed by the StateDataIndex Editorial Team · Updated September 2026.