In plain words

New Mexico has no statewide ADU law. An accessory dwelling unit, or ADU, is a small second home on the same lot as a house. In New Mexico it is often called a casita. Each city and county decides whether to allow them. They do this through zoning. Zoning is the local rulebook for what can be built where. State law does have one narrow rule. Every zoning authority must offer a path to a second kitchen in a single-family zone. It is meant for related family members living together. A city can meet this through a special permit. That rule does not create a separate rentable unit. Lawmakers have tried several times to pass a full ADU law. In 2025, House Bill 554 passed the House 50 to 10, then died in a Senate committee. In 2026, House Bill 17 was tabled in its first committee. Both would have required at least one ADU on every residential lot. Two similar 2023 bills also died. Some cities allow casitas on their own. Albuquerque allows them in its main single-family zones, up to 750 square feet. Santa Fe allows ADUs if the owner records a covenant, which is a promise tied to the land. Homeowners association (HOA) rules can still ban ADUs. Ask about property taxes too, because new construction is valued at today's prices. You may be able to build one if local rules and your property allow it.

The rules at a glance

State ADU lawNo. Each city, town or county decides.
Owner living on siteTowns may require the owner to live on the property.
ParkingState law doesn’t set this. set by each city or county.
SizeState law doesn’t set this. Local limits vary; Albuquerque, for example, caps ADUs at 750 sq ft.
Lot size and setbacksState law doesn’t set this. Local rules vary (a setback is the required gap between a building and a property line); Albuquerque requires a 5 ft setback from the rear or one side lot line.
FeesState law doesn’t set this. Permit and utility fees are set locally.
Short-term rentalsState law doesn’t set this. Cities regulate short-term rentals themselves; Santa Fe, for example, requires a separate city permit for each unit rented for fewer than 30 nights.

What to do next

  1. Find out whether your property is inside city limits or in unincorporated county land, then look up its zoning district.
  2. Read your city's or county's ADU or casita rules, or call the planning office, and ask whether a casita is allowed outright or needs a special permit.
  3. Check HOA covenants and deed restrictions, which can forbid a casita even where zoning allows one.
  4. Ask the county assessor how an ADU would change your property tax, since new construction is valued at current market levels.
  5. If you are in Albuquerque, look at the city's free casita plans; elsewhere, ask whether pre-approved plans exist.
  6. Watch the January 2027 legislative session for a new version of HB 554 or HB 17.

What your town still decides

Under NMSA §3-21-1, each county and municipality is its own zoning authority. It decides building size, lot coverage, yards, density and where homes may go. So whether ADUs (often called casitas in New Mexico) are allowed, and on what terms, is a local choice. The one statewide rule is narrow. Every zoning authority, including home-rule cities, must offer a path, such as a conditional use permit, for a single-family home to have up to two kitchens for a multigenerational family. That allows a second kitchen for relatives, not a separate rental unit. Lawmakers have tried to turn that clause into a real ADU mandate. Bills in 2023, 2025 and 2026 would have required at least one ADU per residential lot, banned owner-occupancy rules, and limited parking and fees. All of them died. The Legislative Finance Committee called the 2026 HB 17 a duplicate of an amended version of the 2025 HB 554. In analyzing HB 554, the Governor's Office of Housing warned that building an ADU can sharply raise a long-time owner's property tax. Residential assessments normally rise no more than 3% a year, but new construction resets value to current market levels. Homeowners association covenants can also bar ADUs; no state law overrides them. The next regular session begins in January 2027.

Examples of local rules

  • Albuquerque: The City Council approved zoning changes in June 2023 that allow casitas in R-1 single-family neighborhoods citywide, and the city's FAQ lists ADUs as allowed in the R-A, R-1, R-T and R-ML zones. An ADU may be up to 750 sq ft, must sit 5 ft from the rear or one side lot line, must be 5 ft from other buildings (or use fire-rated construction), and may not cover more than 25% of the combined side and rear yard area. Approval is through a building permit with full drawings and a scaled site plan. In December 2023 the city released four free casita plan sets of 450 to 750 sq ft, with a goal of 1,000 casitas by 2025. Source
  • Santa Fe: Santa Fe regulates ADUs in Land Development Code §14-6.3(D)(1). ADUs are exempt from the code's density limits, but before a construction permit the owner must record a restrictive covenant. That covenant binds all future owners to the ADU standards and lets the city revoke the certificate of occupancy for violations. An accessory structure with a bathroom or kitchen that is not an ADU requires a signed affidavit limiting its use. Rentals of fewer than 30 nights need a separate short-term rental permit for each unit. Source

What we’re still confirming

  • Albuquerque's casita FAQ doesn't cover owner occupancy, parking, height or short-term rentals; ask the city.

Laws, bills and citations

The laws behind this (1)
  • Two-kitchen rule for multigenerational households (NMSA 1978 §3-21-1(F)-(G) (multigenerational housing clause of the county and municipal zoning authority statute), signed Invalid Date, in effect Invalid Date). Not a full ADU law. It requires every county and city zoning authority, including home-rule cities, to create some way, such as a conditional use permit, to allow up to two kitchens in a single-family zone for multigenerational housing. Multigenerational means people related by blood, marriage, guardianship or adoption. It does not create a separate rentable unit and does not require approval by right. The current wording is shown in the 2026 HB 17 bill text, which would have expanded it. Read it
Proposed and failed bills (4). None of these is law.
  • HB 17 (2026): died as of October 3, 2026. Would have required every county and city, including home-rule cities, to allow at least one attached or detached ADU on every residential lot as a permitted use, regardless of lot size. Localities could not impose owner-occupancy rules, cap ADU size, charge extra impact fees where utilities suffice, or require more than one parking space; they could limit ADUs to rentals longer than 30 days. It also would have required multifamily housing in residential and commercial zones and near major transit. The House Commerce and Economic Development Committee tabled it on February 2, 2026. Bill page
  • HB 554 (2025): died as of October 3, 2026. Would have amended NMSA §3-21-1 so every zoning authority must allow at least one ADU per residential lot as a permitted use, with no owner-occupancy rule, no extra impact fees where utilities suffice, and no more than one parking space. As amended in committee, only HOA restrictions adopted after the bill took effect could not block an ADU permit. It also would have required multifamily housing in commercial zones and near passenger rail. The House passed it 50-10 on March 11, 2025, but it died in the Senate Health and Public Affairs Committee. Bill page
  • HB 425 (2023): died as of October 3, 2026. Would have required zoning authorities to allow one additional dwelling unit of up to 1,000 sq ft on every single-family lot, without discretionary review or a hearing. It would have barred owner-occupancy rules and extra impact fees where utilities suffice, and voided HOA covenants that ban such units; localities could require rentals longer than 30 days. It was referred to the House Government, Elections and Indian Affairs Committee and got no further action. Bill page
  • SB 333 (2023): died as of October 3, 2026. Titled 'Multigenerational Housing & Zoning.' It would have expanded the two-kitchen clause in NMSA §3-21-1(F) to also allow extra detached units for related family members, required every zoning authority to allow one additional dwelling unit on each lot in a single-family zone as a permitted use, and barred new single-family-only zoning districts after July 1, 2023. The Senate Health and Public Affairs Committee recommended passage on February 25, 2023. Its next stop was the Senate Judiciary Committee, and it went no further. Bill page

Sources

  1. NMSA 1978 §3-21-1(F)-(G) (multigenerational housing clause of the county and municipal zoning authority statute) · official source
  2. HB 17 (2026) status page · official source · checked 2026-10-03
  3. HB 17 (2026) Legislative Finance Committee fiscal impact report · official source · checked 2026-10-03
  4. HB 554 (2025) bill text as introduced · official source · checked 2026-10-03
  5. HB 554 (2025) status page · official source · checked 2026-10-03
  6. HB 554 (2025) fiscal impact report, with committee amendments · official source · checked 2026-10-03
  7. HB 425 (2023) bill text · official source · checked 2026-10-03
  8. HB 425 (2023) status page · official source · checked 2026-10-03
  9. HB 425 (2023) fiscal impact report · official source · checked 2026-10-03
  10. SB 333 (2023) status page · official source · checked 2026-10-03
  11. SB 333 (2023) bill text, showing the two-kitchen clause as existing law · official source · checked 2026-10-03
  12. SB 333 (2023) fiscal impact report · official source · checked 2026-10-03
  13. City of Albuquerque: Accessory Dwelling Units (ADUs) FAQs · official source · checked 2026-10-03
  14. City of Albuquerque news: Casita construction just got easier and cheaper (Dec 21, 2023) · official source · checked 2026-10-03
  15. City of Santa Fe: Restrictive Covenant for Accessory Dwelling Unit, per SFCC §14-6.3(D)(1)(i) · official source · checked 2026-10-03
  16. City of Santa Fe: Affidavit restricting use of an accessory structure with a bathroom or kitchen · official source · checked 2026-10-03
  17. City of Santa Fe: Short-term rental application · official source · checked 2026-10-03

This is general information, not legal advice. Your town, village, city or county decides what can be built on your property. If something here looks out of date, email the team.