Taxes collected by California retailers from in-state transactions are called sales taxes. The retailer is responsible for collecting this tax from the customer at the time of sale and for reporting and submitting that tax to the state of California. Also, thanks to California's e-fairness law, out-of-state retailers, including online retailers, are responsible for collecting taxes on sales to California customers. However, in cases where the out-of-state retailer isn't required to charge a sales tax, the customer may be required to pay a "use tax," which is a tax on personal property that is used, stored, or consumed in California. It's a counterpart to the sales tax and you should not ever pay both on the same transaction. Both of these types of taxes go to support California's government.