California is changing the test that decides whether a child can ride with only a seat belt. Starting Jan. 1, 2027, children ages 8 to 15 must pass a 5-step fit check, and any child who fails a step still belongs in a booster seat.
The change comes from Assembly Bill 435, authored by Assembly Member Lori Wilson and approved by the governor on Oct. 7, 2025 as Chapter 434 of the Statutes of 2025. The bill has an operative date of Jan. 1, 2027, which leaves families a little under two months to get used to the idea.
What the 2027 rule changes for children ages 8 to 15
Before the change, an older child could usually graduate to an adult belt once the calendar or the tape measure said so. AB 435 swaps that shortcut for a fit check. According to the bill summary, the five-step test replaces the current definition of “properly restrained” and applies to children 8 to 15 in cars, buses, taxis and limousines. The same belt-fit standard also covers drivers and passengers 16 and older.
The rule follows the child, not the vehicle, so the same check applies in a family car, a taxi or a carpool. Colorado is making a related move for young drivers, and the teen driver education rules coming to Colorado show other states tightening how young people are handled on the road…