Traffic Safety · Car Seat & Booster
Car Seat & Booster Laws in Montana
When your child can move from a booster to a seat belt in Montana, plus rear-facing, front-seat, and the fine, with the law kept separate from best practice.
Prefer a quick check? Run your child's age, height, and weight through the Montana car seat checker →
Check your child's stage in Montana
Enter age, height, and weight. We show the Montana law separately from best practice.
4′9″ = 57 in. Enter only the boxes you have; this state uses the belt is legally OK at age 9 (or earlier if the child passes the booster’s manufacturer height/weight limit); the statute sets no 4′9″ or pound figure of its own.
Educational guide to the minimum legal requirement, not legal or safety advice. Best practice is often stricter than the law. Always follow your car seat’s manufacturer instructions, and confirm the current rule with the official source below (last reviewed 2026-07-11).
The four stages in Montana
Each rung is tagged Law or best practice.
A child under 2 must ride in a rear-facing child safety restraint system that meets federal standards, installed and used per the manufacturer’s instructions.
A child age 2 up to 4 must ride in a rear-facing or forward-facing seat with an internal harness. A child age 4 up to 8 must use a forward-facing harness seat or a booster secured with a lap-shoulder belt.
A child age 4 up to 8 must use a forward-facing harness seat or a booster with a lap-shoulder belt. A child who is at least 9, or who has outgrown the booster’s manufacturer height or weight limit, may use the adult belt.
Exit rule: the belt is legally OK at age 9 (or earlier if the child passes the booster’s manufacturer height/weight limit); the statute sets no 4′9″ or pound figure of its own. The adult belt must fit — lap low across the hips, shoulder belt across the chest.
Front seat, the fine & the source
Seating rule, the exact booster logic, and any recent change.
Montana’s statute does not place children in the rear seat by law. NHTSA recommends children ride in the back seat through age 12; that is guidance, not Montana law.
| Booster exit logic | Age only — no statutory height/weight |
| Seat belt OK | Age 9, or earlier once the child outgrows the booster’s manufacturer height/weight limit |
| First-offense fine | Up to $100 Section 61-9-423 sets a fine of not more than $100. The fine is waived if proof of buying an appropriate child restraint is shown within 7 days of the violation and no prior violation was dismissed this way. |
| Statute | Mont. Code Ann. §61-9-420 (+ §61-9-423) |
Montana replaced its old law (child under 6 AND under 60 lb) with HB 586, effective October 1, 2025. The new age ladder codifies rear-facing under 2, a harness or booster through age 8, and the adult belt at 9. Summaries still quoting "under 6 and 60 lb" describe the repealed rule.
What Montana parents get wrong
Montana rewrote its child-passenger law with HB 586, effective October 1, 2025, so any summary quoting "under 6 and under 60 pounds" is describing the repealed version. The current statute sets a clean age ladder: rear-facing under 2, a rear- or forward-facing harness from 2 up to 4, and a forward-facing harness or booster from 4 up to 8. A child can move to the adult belt at 9, or sooner if they outgrow the booster’s manufacturer limit. Unlike states that legislate rear-seat placement, Montana does not put children in the back by law; the NHTSA "back seat through 12" line is guidance here. The first-offense fine is capped at $100 and is waived if you show proof of buying a proper restraint within 7 days.
Common questions
When can a child stop using a booster in Montana?
At age 9, or earlier if the child outgrows the booster’s manufacturer height or weight limit. Montana’s statute uses age, not a 4′9″ mark. This reflects the HB 586 rules effective October 1, 2025.
Does Montana require rear-facing car seats by age?
Yes. Since October 1, 2025, a child under 2 must ride in a rear-facing child safety restraint system by law, not just as a recommendation.
What changed in Montana’s car seat law in 2025?
HB 586 replaced the old "under 6 and under 60 pounds" rule with an age ladder: rear-facing under 2, harness or booster from 2 to 8, and the adult belt at 9. It took effect October 1, 2025.
What is the fine for a car-seat violation in Montana?
Up to $100. The fine is waived if you show proof within 7 days that you bought an appropriate child restraint and no earlier violation was dismissed the same way (§61-9-423).
Do children have to ride in the back seat in Montana?
Not by statute. Montana does not legislate rear-seat placement. NHTSA still recommends the back seat through age 12, but that is guidance, not Montana law.
Not legal advicePlainStatute provides plain-language summaries of public law for general information only. This is not legal advice. Statutes change; always confirm current requirements with the official source linked above before acting.