Colorado Car Seat Requirements by Age and Weight

Colorado car seat laws require every child under 18 to be properly restrained in a motor vehicle, with the type of restraint — rear-facing seat, forward-facing seat, booster, or seat belt — determined by the child’s age and weight under C.R.S. § 42-4-236.¹ The driver is legally responsible for every minor passenger, and this is a primary enforcement law, so an officer can pull you over based on an unrestrained child alone.²

Under 2 Years Old

Children younger than 2 must ride in the back seat whenever the vehicle has one, and they must be in a rear-facing car seat if they weigh less than 40 pounds. A child under 2 who weighs more than 40 pounds may ride in a rear-facing or forward-facing seat, whichever fits within the seat manufacturer’s limits.³

NHTSA recommends keeping a child rear-facing as long as possible, up to the height or weight maximum the seat manufacturer allows, even past age 2.⁴

Ages 2 and 3

Two- and three-year-olds must also ride in the back seat when one is available. Under 20 pounds, the child stays rear-facing. Over 20 pounds, either rear-facing or forward-facing is allowed.³ Most children this age are well past 20 pounds, so the practical choice is whether to keep them rear-facing for the added protection or switch to a forward-facing harness. Either is legal.

Ages 4 Through 8

Children 4 through 8 must ride in the back seat when the vehicle has one. Weight sets the restraint:

Under 40 pounds: rear-facing or forward-facing car seat with a harness.
Over 40 pounds: forward-facing car seat or a booster seat.

A booster is doing its job when the shoulder belt crosses the center of the chest and shoulder without touching the neck, and the lap belt sits low across the upper thighs rather than the stomach.³ If the belt doesn’t sit right, the child still needs the booster regardless of age.

Ages 9 Through 17

From age 9 through age 17, a child must be properly restrained in a booster seat or a seat belt. The shoulder belt has to cross the shoulder and chest without touching the neck or face, and the lap belt has to lie flat across the upper thighs.³ Colorado does not require the back seat for this age group, but NHTSA recommends the back seat through at least age 12.⁴

Age 9 is where families often abandon boosters, but a smaller child whose shoulder belt still cuts across the neck needs to stay in one. Fit, not just birthdays, decides.

Back Seat and Airbag Rules

Colorado law requires children under 9 to sit in the back seat whenever one is available.³ A rear-facing car seat should never be placed in front of an active passenger-side airbag. An airbag deploys with enough force to cause fatal injuries to a child in a rear-facing seat directly in front of it.⁵ If the vehicle only has a front row, deactivate the passenger airbag before installing any child restraint there and follow both the car seat and vehicle manufacturer instructions.

Exemptions

C.R.S. § 42-4-236(3) carves out only a few narrow situations where the restraint requirement doesn’t apply:

A child under 9 being transported during a medical or other life-threatening emergency when no child restraint is available.
Children riding in vehicles operated by or on behalf of a common carrier, contract carrier, or luxury limousine service, which covers taxis and commercial buses.
Children transported in a commercial motor vehicle operated by a child care center.

The statute contains no physician-letter exemption. The medical carve-out is for emergency transport when a seat isn’t available, not for ongoing use.⁶ A child with a medical condition that makes standard restraints difficult needs an adaptive car seat, and a certified child passenger safety technician can help identify one.

Fines and Enforcement

An improper child restraint is a class B traffic infraction.⁶ The Colorado State Patrol reports a minimum fine of $82 per improperly restrained child, and the driver can be fined separately for each one in the vehicle.² Because this is a primary enforcement law, an officer needs no other reason to stop the vehicle. Class B infractions do not add demerit points to the driver’s license, so the consequence is financial rather than a hit to your record.⁷ Insurance adjusters also examine whether a child was correctly restrained when evaluating injury claims after a crash.

Free Inspections and When to Replace a Seat

Colorado offers free car seat inspections through certified technicians across the state, and the Colorado Department of Transportation keeps a directory of inspection stations.⁸ A large share of seats are installed incorrectly, so the check is worthwhile even if you’re confident.

Car seats also have expiration dates, typically six years from the date of manufacture, printed on a label on the shell. Replace any seat that has been in a moderate or severe crash even if it looks fine. Registering your seat with the manufacturer or through NHTSA at 1-888-327-4236 will get you automatic recall notices. All child restraints used in Colorado must meet Federal Motor Vehicle Safety Standards, and when a child fits two categories, the more protective seat is the safer choice as long as they’re within the manufacturer’s height and weight limits.³

1
Colorado General Assembly. HB24-1055 Child Passenger Safety and Education
2
Colorado State Patrol. Under 18, Seatbelts Are Primary Enforcement Law
3
Colorado Department of Transportation. Colorado Child Passenger Safety Law
4
NHTSA. Car Seat Recommendations for Children
5
Colorado Department of Transportation. Frequently Asked Questions
6
Colorado Public Law. Colorado Code 42-4-236 – Child Restraint Systems Required
7
FindLaw. Colorado Revised Statutes Title 42 – Section 42-4-1701
8
Colorado Department of Transportation. Car Seats Colorado