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Montana car seat laws

Mont. Code Ann. § 61-9-420 · Last checked September 23, 2026

Car seat stages

The statute text comes first. Numbers are a summary for comparison, not a replacement for the law.

Rear-facing seat

Statute text

A motor vehicle passenger who is under 2 years of age must be properly restrained in a rear-facing child safety restraint system that complies with federal motor vehicle safety standards.

MCA § 61-9-420(1).

What the law sets

Rear-facing seat required by law
Yes
Rear-facing until age
2 years
Rear-facing until weight
Not addressed in statute

Not set in § 61-9-420.

Rear-facing until height
Not addressed in statute

Not set in § 61-9-420.

Leaving rear-facing
Meeting any one listed limit is enough

Age is the only limit: rear-facing is required under two.

Recommended (not law)

NHTSA

Children under age 1 should always ride in a rear-facing car seat. Keep your child rear-facing as long as possible — it's the best way to keep them safe — until they reach the top height or weight limit allowed by the car seat's manufacturer.

NHTSA – Car Seats and Booster Seats

AAP

All infants should ride rear-facing, starting with their first ride home from the hospital, and should continue riding rear-facing as long as possible until they reach the highest weight or height allowed by their car safety seat's manufacturer.

HealthyChildren.org (AAP) – Car Safety Seats: Information for Families

Forward-facing harness seat

Statute text

A motor vehicle passenger who is between 2 years of age and up to 4 years of age must be properly restrained in a rear-facing or forward-facing child safety restraint system with an internal harness that complies with federal motor vehicle safety standards.

MCA § 61-9-420(2).

What the law sets

Forward-facing harness required by law
Yes

A harness seat is required; it may face rear or forward.

Harness until age
4 years
Harness until weight
Not addressed in statute

Not set in § 61-9-420.

Harness until height
Not addressed in statute

Not set in § 61-9-420.

Leaving the harness
Meeting any one listed limit is enough

Age is the only limit: the harness is required from two up to four.

Recommended (not law)

NHTSA

Once a child outgrows the rear-facing car seat, they are ready for a forward-facing car seat with a harness and tether. Keep the child in the forward-facing seat until they reach the top height or weight limit allowed by the car seat's manufacturer, then move to a booster seat, still in the back seat.

NHTSA – Car Seats and Booster Seats

AAP

Children should use a forward-facing car seat with a harness after outgrowing the rear-facing weight or height limit. It is best for children to ride in a seat with a harness as long as possible, at least to 4 years of age.

HealthyChildren.org (AAP) – Car Safety Seats: Information for Families

Booster seat

Statute text

A motor vehicle passenger who is between 4 years of age and up to 8 years of age must be properly restrained in a forward-facing child safety restraint system with an internal harness or a child booster seat that is secured with a vehicle lap-shoulder seat belt, whichever is applicable, that complies with federal motor vehicle safety standards.

MCA § 61-9-420(3). Subsection (4) then requires an adult safety belt at 9 years of age or on outgrowing the booster's manufacturer limits, whichever comes first, so the statute does not say which restraint applies to an 8-year-old who still fits a booster.

What the law sets

Booster required by law
Yes

A harness seat or a booster is required.

Booster until age
8 years

Subsection (3) ends at 8; subsection (4) sets the adult belt at 9 or on outgrowing the booster's manufacturer height or weight limit, whichever comes first.

Booster until weight
Not addressed in statute

No number in MCA § 61-9-420; subsection (4) uses the booster's manufacturer weight limit.

Booster until height
Not addressed in statute

No number in MCA § 61-9-420; subsection (4) uses the booster's manufacturer height limit.

Leaving the booster
Meeting any one listed limit is enough

A child leaves the booster on reaching the age in subsection (3)/(4) or on outgrowing the booster's manufacturer limits, whichever comes first.

Recommended (not law)

NHTSA

Keep your child in a booster seat until they are big enough to fit in a seat belt properly — the lap belt lying snugly across the upper thighs (not the stomach) and the shoulder belt snug across the shoulder and chest (not the neck or face).

NHTSA – Car Seats and Booster Seats

AAP

All children whose weight or height exceeds the forward-facing limit for their car safety seat should use a belt-positioning booster seat until the vehicle seat belt fits properly, typically when they have reached 4 feet 9 inches in height and are 8 to 12 years of age.

HealthyChildren.org (AAP) – Car Safety Seats: Information for Families

Seat belt

Statute text

A motor vehicle passenger who is at least 9 years of age or has outgrown the height or weight limits of a child booster seat as set by the manufacturer, whichever comes first, must be secured with a motor vehicle adult safety belt.

MCA § 61-9-420(4).

What the law sets

Seat belt alone from age
9 years

MCA § 61-9-420(4) names 9, while subsection (3) ends the booster stage at 8.

Seat belt alone from height
Not addressed in statute

No number in MCA § 61-9-420(4); the alternative to age is the booster's manufacturer height or weight limit.

Moving to the seat belt
Meeting any one listed limit is enough

Recommended (not law)

NHTSA

Once a child is big enough to fit in a seat belt properly, they can ride with just the lap-and-shoulder belt, but should still ride in the back seat — NHTSA recommends keeping children in the back seat at least through age 12.

NHTSA – Car Seats and Booster Seats

AAP

Children should transition to the vehicle seat belt once it fits properly, typically at about 4 feet 9 inches in height and 8 to 12 years of age; all children younger than 13 years should ride in the back seat.

HealthyChildren.org (AAP) – Car Safety Seats: Information for Families

Front seat

Many states have no front-seat age in statute. Where that is the case, we say so and cite the section we read.

Front seat — statute text
Not addressed in statute

No front-seat provision in MCA § 61-9-420.

Minimum age for the front seat
Not addressed in statute

No front-seat provision in MCA § 61-9-420.

Conditions
Not addressed in statute

No front-seat provision in MCA § 61-9-420.

Penalties

What a car seat ticket costs, and whether showing proof of a proper seat can cancel it.

First offense — fine
Up to $100

MCA § 61-9-423(1): a violation of § 61-9-420 is punishable by a fine of not more than $100.

Repeat offense — fine
Up to $100

MCA § 61-9-423 sets one maximum for every violation; there is no separate repeat penalty.

License points
2 points

MCA § 61-9-420 sets no points itself. A conviction is a "moving violation" as defined in § 61-11-203(1)(d) and is not separately listed in (2)(a)-(l), so the catch-all in § 61-11-203(2)(m), "all other moving violations, 2 points", applies. This value is inferred from the catch-all, not from a provision that names § 61-9-420.

Fine waiver
The fine must be waived if proof of acquiring an appropriate child safety restraint is presented within 7 days of the violation to the charging officer's office and no previous violation has been dismissed this way (MCA § 61-9-423(2)).

Exemptions

Exempt means the statute excludes it. Silent means the statute does not address it.

Taxis
Exempt

MCA § 61-9-421(1) makes § 61-9-420 inapplicable to a taxicab.

Rideshare (Uber, Lyft)
Not addressed in statute

MCA §§ 61-9-420 and 61-9-421 do not name transportation network companies; whether the taxicab exemption reaches them is not stated.

Buses
Exempt

MCA § 61-9-421(1) names school buses and any vehicle not required to be equipped with safety belts under 49 CFR 571 as it reads on January 3, 2025.

Medical exemption
Exempt

MCA § 61-9-420(6) lets the department exempt by rule a child who because of a physical or medical condition or body size cannot be placed in a child safety restraint system; the statute itself grants no automatic exemption. MCA § 61-9-421(3) also suspends the rule in a life-threatening emergency.

Out-of-state vehicles
Not addressed in statute

MCA §§ 61-9-420 and 61-9-421 do not address nonresident drivers or out-of-state vehicles.

How Montana compares

Montana is tied for 6th of 47 jurisdictions with a numeric booster age: 33 jurisdictions, including Montana, require a booster until age 8.

Compared with Idaho, North Dakota, South Dakota, and Wyoming, Montana differs on: rear-facing rules (from Idaho, North Dakota, South Dakota, and Wyoming), booster rules (from Idaho, North Dakota, South Dakota, and Wyoming), and front-seat rules (from Wyoming).

Law compared with the AAP recommendation

  • Montana law: a rear-facing seat is required until the child reaches age 2. AAP recommends: All infants should ride rear-facing, starting with their first ride home from the hospital, and should continue riding rear-facing as long as possible until they reach the highest weight or height allowed by their car safety seat's manufacturer.
  • Montana law: a forward-facing harness seat is required until the child reaches age 4. AAP recommends: Children should use a forward-facing car seat with a harness after outgrowing the rear-facing weight or height limit. It is best for children to ride in a seat with a harness as long as possible, at least to 4 years of age.
  • Montana law: a booster seat is required until the child reaches age 8. AAP recommends: All children whose weight or height exceeds the forward-facing limit for their car safety seat should use a belt-positioning booster seat until the vehicle seat belt fits properly, typically when they have reached 4 feet 9 inches in height and are 8 to 12 years of age.
  • Montana law: a child may use the seat belt alone once reaching age 9. AAP recommends: Children should transition to the vehicle seat belt once it fits properly, typically at about 4 feet 9 inches in height and 8 to 12 years of age; all children younger than 13 years should ride in the back seat.

See every state side by side on the comparison pages.

Sources

State law comes from the statute or state agency below. Recommendations come from NHTSA and the American Academy of Pediatrics. The responsible agency is Montana Department of Transportation, State Highway Traffic Safety Section.

State law

Recommendations

Disclaimer

This page summarizes Montana law for reference. It is not legal or medical advice. The statute text is the law; the numbers are our summary of it. Legal minimums are not safety recommendations: NHTSA and the AAP recommend keeping a child in each stage for as long as the seat allows. Check the statute or Montana Department of Transportation, State Highway Traffic Safety Section before relying on anything here.