New Mexico Booster Seat Law (2026)

New Mexico is upgraded to an official-source page because its statute does something unusual: it writes the seat-belt fit test directly into law, not just into safety guidance.

For 2026 checks, the direct answer is: rear-facing under 1 (in the rear seat, with a front-seat exception only if there is no rear seat and the passenger airbag is off or absent); ages 1 through 4 or under 40 lb in a restraint device; ages 5 through 6 or under 60 lb in a booster or restraint device; ages 7 through 12 in a restraint device or seat belt.

Subsection C of the statute defines a properly secured seat belt: the lap belt across the thighs and hips, not the abdomen, and the shoulder strap across the center of the chest, not the neck, with the child sitting all the way back and knees bent at the seat edge. That is the same test safety organizations recommend nationally, written into New Mexico law itself.

Under 1 year: rear-facing restraint device in the rear seat. If the vehicle has no rear seat, the front seat is allowed only if the passenger-side air bag is deactivated or the vehicle has no deactivation switch for it.

Ages 1 through 4, or under 40 pounds regardless of age: a child passenger restraint device meeting federal standards.

Ages 5 through 6, or under 60 pounds regardless of age: a child booster seat or an appropriate child passenger restraint device.

Ages 7 through 12: a child passenger restraint device or a seat belt.

Subsection C of 66-7-369 states: a child is properly secured in an adult seat belt when the lap belt fits across the thighs and hips, not the abdomen, and the shoulder strap crosses the center of the chest, not the neck, with the child sitting all the way back against the vehicle seat and knees bent at the seat edge.

That is the same fit test safety organizations recommend nationally, but New Mexico is one of the few states to write it into the statute itself rather than leaving it to separate safety guidance.

The restraint requirement does not apply if all seating positions equipped with safety belts are already occupied. This is a practical carve-out for large families, not permission to skip a restraint when a belted seat is free.

The statute does not apply to authorized emergency vehicles, public transportation, or a school bus.

New Mexico Statutes 66-7-369 sets a penalty assessment of $25 for a violation.

New Mexico Statutes 66-7-369 sets a penalty assessment of $25 for a violation.

No. New Mexico Statutes 66-7-369 covers passengers under 18; the age and weight tiers are for children. A viral notice claiming New Mexico requires adults under a certain height to use booster seats is not this law; see the adult booster seat law fact check. Searches using the phrase "adult booster seat" usually mean the point when a child can move from a booster to the adult seat belt.

Not sure which type fits your child? Use the seat finder — enter age, height, and weight to see the stage and a matching seat.