Can I Build an ADU (Accessory Dwelling Unit) in New Mexico?
Quick Answer
Often yes — many states now require cities to allow at least internal ADUs.
State Law May Require It
A growing number of states have passed laws requiring cities to allow at least internal ADUs (within the existing footprint of the home — basement apartments, above-garage units, etc.). Many cities also allow detached ADUs, though rules on size and placement vary. Check whether your state has an ADU-enabling law before assuming your city can simply say no.
Types of ADUs
Internal ADUs include basement apartments, converted attic space, and attached additions. Detached ADUs include backyard cottages, converted garages, and purpose-built accessory structures. Each type has different permit requirements and setback rules.
Key Requirements
Most ADUs need: a separate entrance from the primary dwelling, adequate parking (usually one additional off-street space), fire separation (1-hour rating for internal ADUs), and compliance with all building codes for habitable space. Basement ADUs require egress windows in every bedroom.
Reduced Impact Fees
Some states limit impact fees for ADUs, making them cheaper to permit than a full second dwelling. Many cities waive or significantly reduce impact fees for ADUs. Ask your city about current fee schedules — this can save thousands of dollars.
Bottom Line
In many states you can build an ADU thanks to state law requiring cities to allow it. Internal ADUs are the easiest path. Start by checking your state's ADU law and your city's specific ADU ordinance.
Permit fees by city in New Mexico
Verified from each city’s published fee schedule. Where a city has no separate fee listed for this project, open the city page for the current requirements and amount.
| City | Permit fee | Source |
|---|---|---|
| Alamogordo | $85Verifiedvia Residential Building Permit (New Construction) | Residential Building Permit (New Construction) → |
| Albuquerque | Same Table 112-A formula and 0.50 regional modifier as new residential construction, applied to the casita's building valuationVerified | Accessory Dwelling Unit (ADU / Casita) Permit → |
| Clovis | $28.00 + $5.60 per $1,000 of valuationVerifiedvia Residential Building Permit (New Construction) | Residential Building Permit (New Construction) → |
| Farmington | See city page for the current Residential Building Permit (New Construction) fee | Residential Building Permit (New Construction) → |
| Hobbs | $20.00Verifiedvia Residential Building Permit (New Construction) | Residential Building Permit (New Construction) → |
| Las Cruces | $0.20 per square foot of gross floor area; minimum permit fee $50Verified | Accessory Dwelling Unit (ADU) Permit → |
| Rio Rancho | 65% of the Building Permit Fee (non-refundable)Verified | Accessory Dwelling Unit (ADU) Permit → |
| Roswell | $24.00Verifiedvia Residential Building Permit | Residential Building Permit → |
| Santa Fe | Assessed on construction valuation using the primary Building Permit fee tableVerified | Accessory Dwelling Unit (Guesthouse) Permit → |
| Unincorporated Bernalillo County | $30.00 plus $4.00 per $1,000.00 of valuationVerified | Accessory Dwelling Unit (Secondary Dwelling Unit / Accessory Living Quarters) → |