Cal. RTC § 6201

An excise tax is hereby imposed on the storage, use, or other consumption in this state of tangible personal property purchased from any retailer on or after July 1, 1935, for storage, use, or other consumption in this state at the rate of 3 percent of the sales price of the property, and at the rate of 2 1/2 percent on and after July 1, 1943, and to and including June 30, 1949, and at the rate of 3 percent on and after July 1, 1949, and to and including July 31, 1967, and at the rate of 4 percent on and after August 1, 1967, and to and including June 30, 1972, and at the rate of 3 3/4 percent on and after July 1, 1972, and to and including June 30, 1973, and at the rate of 4 3/4 percent on and after July 1, 1973, and to and including September 30, 1973, and at the rate of 3 3/4 percent on and after October 1, 1973, and to and including March 31, 1974, and at the rate of 4 3/4 percent thereafter.