California parents and caregivers will see an important change to child passenger safety laws beginning January 1, 2027. Assembly Bill 435, also known as AB 435, changes how California law defines when certain children are properly restrained by a vehicle safety belt.
The new law does not simply replace California’s existing car seat and booster seat requirements. Instead, it establishes a statutory 5-Step Test for determining whether a child between the ages of 8 and 15 is properly restrained by a safety belt.
Understanding California car seat laws can help parents make informed decisions about when to transition a child from a car seat or booster to a vehicle safety belt. It can also help families understand their options if a child is injured in a car accident.
What Is AB 435?
AB 435 is a California law concerning child passenger restraints. Governor Gavin Newsom signed the bill on October 7, 2025. Although the law was enacted in 2025, the relevant provisions regarding the 5-Step Test become operative on January 1, 2027.
The law addresses children who are at least 8 years old but under 16 years old. Under the new law, a child in this age range must be properly secured in an appropriate child passenger restraint system that meets applicable federal motor vehicle safety standards, or be properly restrained by a safety belt.
Beginning January 1, 2027, a child is considered properly restrained by a safety belt only if the child meets all five requirements of the statutory 5-Step Test.
This distinction matters because age alone does not necessarily mean a child is ready to use an adult safety belt without a booster. The fit of the belt on the individual child is important.
California Child Passenger Restraint Requirements By Age
The following chart provides a general guide to California’s child passenger restraint requirements. Parents should also follow the height and weight limits provided by the manufacturer of the specific child restraint.
| Child’s Age | California Requirement | Typical Type of Restraint |
| Under 2 | Must ride in a rear-facing child passenger restraint system unless the child weighs at least 40 pounds or is at least 40 inches tall. | Rear-facing car seat |
| 2 through 7 | Generally must be properly secured in an appropriate car seat or booster seat in the rear seat. A child who is under 8 but at least 4 feet, 9 inches tall may use a safety belt. | Forward-facing car seat with harness, followed by a booster seat when the child outgrows the harness |
| 8 through 15 | Must be properly secured in an appropriate child passenger restraint system or properly restrained by a safety belt. Beginning January 1, 2027, a safety belt must satisfy the statutory 5-Step Test. | Booster or other appropriate restraint if the safety belt does not fit properly, or a lap-and-shoulder belt when the child meets the requirements |
| 16 and older | Subject to California’s mandatory safety belt requirements. | Seat belt |
California law includes specific exceptions, so this chart should be viewed as a general guide rather than a substitute for reviewing the applicable law and the instructions for a child’s specific restraint. California Highway Patrol and the Office of Traffic Safety also recommend keeping children in each stage of restraint as long as possible rather than moving them to the next stage based solely on age.
What Is The 5-Step Test?
The 5-Step Test helps determine whether a vehicle’s safety belt fits a child properly.
Beginning January 1, 2027, all five requirements will be part of California’s statutory definition of being properly restrained by a safety belt for children covered by AB 435.
1. The Child Sits All The Way Back
The child’s back should rest completely against the vehicle seat.
A child who has to lean forward or cannot comfortably sit against the seatback may not be ready to use the vehicle’s safety belt without additional support.
2. The Child’s Knees Bend At The Edge Of The Seat
The child’s knees should bend comfortably over the edge of the vehicle seat.
If the child has to slide forward to bend their knees, the seat belt may not fit correctly.
3. The Shoulder Belt Crosses The Chest And Shoulder
The shoulder portion of the belt should cross the center of the child’s chest and shoulder. It should not cross the child’s neck.
A belt that rests against the neck can indicate that the child is too small for the vehicle’s safety belt to fit properly.
4. The Lap Belt Sits Low on the Thighs
The lap portion of the belt should sit as low as possible and touch the child’s thighs.
It should not ride up onto the child’s abdomen.
5. The Child Can Maintain the Position
The child must be able to remain seated properly for the entire trip.
This final step is important because a child who repeatedly moves the belt behind their back, places the shoulder belt under their arm, or changes position may not be ready to use the vehicle safety belt without additional support.
California’s Department of Public Health and California Highway Patrol both describe these five elements when discussing proper safety belt fit.
Does AB 435 Eliminate Booster Seats?
No.
AB 435 does not eliminate booster seats or establish a rule that every child must stop using a booster at age 8.
Instead, the law addresses whether a child between 8 and 15 is properly restrained by a safety belt. If the vehicle’s safety belt does not fit the child correctly, parents may need to continue using an appropriate child passenger restraint system, such as a belt-positioning booster, until the child is large enough for the vehicle’s safety belt to fit properly.
California Highway Patrol recommends that parents do not rush children out of booster seats. Its guidance states that children should continue using belt-positioning booster seats until they are tall enough for the vehicle safety belt to fit properly.
The California Department of Public Health similarly advises parents to use a booster seat until the child is big enough for the seat belt to fit properly and provides the 5-Step Test as a way to evaluate that fit.
When Should A Child Move From A Car Seat To A Booster?
California law does not establish one universal age at which every child must move from a forward-facing harnessed car seat to a booster seat.
Instead, parents should follow the height and weight limits provided by the car seat manufacturer.
California Highway Patrol advises keeping a child in a forward-facing harnessed seat until the child reaches the height or weight limit specified by the manufacturer. CHP notes that these limits are commonly between 40 and 65 pounds, but parents should always check the specific seat’s instructions.
Once a child has outgrown a forward-facing harnessed seat, a belt-positioning booster can help position the vehicle’s lap and shoulder belt correctly across the child’s body.
When Is a Child Ready to Stop Using a Booster?
The most important consideration is not simply whether a child has reached a certain birthday.
The vehicle’s safety belt should fit the child correctly.
Parents can use the 5-Step Test as a practical way to evaluate whether the child is ready:
- Does the child sit all the way back against the seat?
- Do the child’s knees bend comfortably at the edge of the seat?
- Does the shoulder belt cross the chest and shoulder without touching the neck?
- Does the lap belt sit low across the thighs?
- Can the child remain in the proper position for the entire trip?
If the answer to any of these questions is no, the child may need additional support from a booster seat.
Where Should Children Sit in a Vehicle?
California law generally requires children under 8 to ride in an appropriate child passenger restraint system in the rear seat, subject to statutory exceptions.
The California Office of Traffic Safety also recommends that all children 13 and under ride in the back seat.
Parents should also review their vehicle owner’s manual and the child restraint manufacturer’s instructions when determining where and how a particular car seat or booster should be installed.
Car Seat Installation Matters
Choosing the appropriate car seat or booster is only part of child passenger safety. The restraint also needs to be installed and used correctly.
California Highway Patrol encourages parents who are unsure about their child’s car seat installation to contact a local CHP Area Office and speak with a child passenger safety technician. CHP provides child safety seat inspections and educational resources throughout California.
Parents should pay attention to:
- The manufacturer’s installation instructions
- Height and weight limits
- Harness positioning
- Whether the seat is installed securely
- Proper use of the vehicle’s seat belt or lower anchors
- Whether the child is positioned correctly in the restraint
- Whether the restraint has been involved in a crash and needs to be replaced
Because child restraint systems differ, parents should always consult the manufacturer’s instructions for their specific seat.
What If A Child Is Injured In A Car Accident?
Even when a child is properly restrained, a serious collision can cause significant injuries.
Children may suffer injuries involving the head, neck, spine, chest, abdomen, or other parts of the body. Some injuries may be immediately apparent, while others may require medical evaluation before the full extent becomes clear.
After a collision involving a child, parents should prioritize medical care and follow the child’s healthcare provider’s recommendations.
It is also important to preserve information about the collision and the child’s injuries, including:
- Medical records
- Emergency department records
- Follow-up appointments
- Photographs of visible injuries
- Information about the vehicle and child restraint
- Photos of the crash scene and vehicles
- Insurance information
- The police collision report
- Statements from witnesses
- Documentation of missed school or activities
If another driver’s negligence caused the collision, the circumstances of the crash and the resulting injuries may be relevant to a personal injury claim.
What Parents Should Know About The 2027 Change
The biggest thing for parents to understand about AB 435 is that January 1, 2027, does not mean every 8-year-old should immediately stop using a booster seat.
The law establishes a more specific standard for determining when a child between 8 and 15 is properly restrained by a safety belt.
A child who is still too small for the vehicle’s safety belt to fit correctly may continue to need an appropriate child passenger restraint system. Parents should consider the child’s individual size, the fit of the safety belt, the manufacturer’s instructions, and the 5-Step Test.
The goal is to make sure the restraint being used actually fits the child.
California Car Seat Law FAQ
Does California’s new 2027 car seat law require every 8-year-old to use a booster seat?
No. AB 435 does not create a blanket requirement that every 8-year-old use a booster seat. Beginning January 1, 2027, it establishes the 5-Step Test for determining whether a child between 8 and 15 is properly restrained by a safety belt.
What is the 5-Step Test?
The test asks whether the child can sit all the way back against the seat, bend their knees at the edge of the seat, have the shoulder belt properly positioned across the chest and shoulder, have the lap belt sitting low on the thighs, and remain in that position for the entire trip.
Can my child still use a booster seat after age 8?
Yes. A child may continue using an appropriate booster or other child passenger restraint system when the vehicle’s safety belt does not fit properly.
Does California require children to ride in the back seat?
California generally requires children under 8 to be secured in an appropriate restraint in the rear seat, subject to statutory exceptions. The California Office of Traffic Safety recommends that children 13 and under ride in the back seat.
When does AB 435 take effect?
The relevant provisions of AB 435 become operative on January 1, 2027.
What should I do if my child was injured in a car accident?
Seek appropriate medical care first. Preserve medical records and other documentation related to the collision and your child’s injuries. If another driver’s negligence caused the accident, consider speaking with a personal injury attorney about your legal options.
How Fielding Law Can Help After A California Car Accident
A car accident involving a child can be overwhelming for parents. In addition to dealing with medical care and recovery, families may have questions about insurance, responsibility for the collision, medical expenses, and their legal options.
Fielding Law represents individuals and families throughout California in personal injury cases involving car accidents and other types of negligence-based injuries.
Our approach is centered on individualized representation. Clients are people, not case numbers, and we work to understand the circumstances of each person’s injuries and how the accident has affected their life.
If your child was injured in a California car accident caused by someone else’s negligence, our team can review the circumstances of the collision and explain your options.
Contact Fielding Law today at 833.88.SHARK to schedule a free consultation.
Fielding Law, APC – Irvine, CA Office
505 Technology Dr Ste 250
Irvine, CA 92618
(949) 288-5484
Fielding Law, APC – Phoenix, AZ Office
2 N Central Ave Ste 1800
Phoenix, AZ 85004
(859) 578-4444
Note: Information provided is for educational purposes and does not constitute legal advice. Always consult with a qualified attorney for legal concerns.
