A child can switch from a car seat to a booster seat at age 4 if he weighs at least 40 pounds, according to the Texas Department of Public Safety. The department recommends the use of a booster seat with shoulder belt and adult lap belt.
Following the 2013 child safety national best practice recommendations, booster seats must be used until children comfortably can use adult safety belts, reports the Texas Department of Public Safety. This is usually at 10 to 12 years old, at a minimum height of 4 feet 9 inches. Children must be properly restrained and ride only in the back seat until age 13.