If you live in the unincorporated areas outside of the cities of La Mesa or El Cajon but share their zip code you will be overcharged when you pay sales tax on a new or used car, boat, trailer, motor home and who knows what else.
How does that happen? On these large items you are charged the tax rate based on your residence address. I bought a new car in November. The dealer's software ingested my zip code (92020) and charged me the El Cajon sales tax rate which is one per cent higher (8.75% vs. 7.75%). I was out $216. I caught the error but the dealer did not know how to override the software. Two weeks later I did received the $216 refund.
A neighbor just bought two new cars and was unaware he'd been overcharged $700 until I suggested he check his paperwork. Anyone who's bought a large item and the sales tax is based on their home address should go back and check the paperwork to see if they were charged more than 7.75%. If so request (demand) a refund of the overcharge. The seller is not out the refund. According to the Board of Equalization they only have to note the refund on their quarterly tax report.
When you buy a large item in the future make sure you are only charged the county sales tax rate.
If you live in San Diego county and not in a city your sales tax rate is 7.75% (until January 1, 2013 when the rate increases 8.00%).
Zip codes shared by city and Mt. Helix/Rancho San Diego residents include 92020, 92019, 91941.