California vs Texas

California and Texas end up in nearly the same place for older kids, but they start from very different rules for the youngest ones. California writes two protections into statute that Texas does not. First, a child under 2 must ride rear-facing unless they already weigh 40 pounds or stand 40 inches tall. Second, a child under 8 must ride in the back seat where one is available. Texas law sets neither rule. It requires a child under 8 (and under 4 feet 9 inches) to be in a child safety seat used per the manufacturer's instructions, and it leaves the choice of rear-facing, forward-facing, or booster to the parent.

That does not mean rear-facing is optional for safety in Texas. Pediatricians recommend keeping a child rear-facing as long as the seat allows in both states. It means only that California makes rear-facing under 2 a legal requirement a parent can be cited for, while Texas treats it as a manufacturer-and-best-practice matter.

Here the two states match. Both require a child to stay in a car seat or booster until age 8 or until they reach 4 feet 9 inches (about 57 inches), whichever comes first. A child who is 8, or who is shorter than 8 but has reached 4 feet 9 inches, may legally use the adult seat belt in either state. So if your question is purely about when the booster comes out, California and Texas give the same answer. The American Academy of Pediatrics still recommends keeping a child in a booster until the belt fits correctly across the shoulder and hips, which is usually closer to 4 feet 9 inches and somewhere between ages 8 and 12.

The law that applies is the law of the state you are physically driving in, not the state where you live or where the car is registered. Cross into California and California's rules apply; cross back into Texas and Texas governs. On an I-10 road trip between the two, the simplest way to stay legal the whole way is to follow the stricter of the two rules: keep a child under 2 rear-facing and any child under 8 in the back seat. Do that and you satisfy California's stricter requirements while still falling comfortably inside what Texas asks for. Families relocating from Texas to California most often get caught by the rear-facing-under-2 and back-seat rules, because Texas never required either one.

Texas treats a violation as a misdemeanor with a fine of $25 to $250, and a first-time offender who did not own a seat can have the charge dismissed by obtaining an appropriate one. California's base fine is commonly cited at $100 for a first offense and $250 for each later offense, but state and county penalty assessments push the actual amount payable substantially higher, and the total varies by county. In practice California's penalty runs higher than the Texas range once assessments are added. Both states write a parent-present exception into how the rule is applied, and the back-seat and rear-facing citations are unique to California.

California is the state to watch. Starting January 1, 2027, Assembly Bill 435 redefines what counts as a child being properly restrained by a seat belt. The belt must pass a five-step fit test: the child sits all the way back against the seat, their knees bend comfortably over the seat edge, the shoulder belt crosses the center of the chest and shoulder rather than the neck, the lap belt sits low and touches the thighs, and the child can hold that position for the whole trip. A child who cannot pass must stay in a booster, even after reaching 8 years or 4 feet 9 inches. Texas has no comparable rule. So while the two states are even on booster age today, California is set to pull ahead in 2027 by tying graduation to fit rather than to age alone.