Most states that have a sales tax also have a use tax. You are supposed to pay the use tax on items you purchase out of state for use in-state. In the past, use tax was only paid voluntarily in most cases (although, if you bought a vehicle out of state, the state would make you pay the use tax when you registered it). Today, many states put the use tax on your state income tax return and ask you to voluntarily disclose the cost of items you bought out of state that you did not pay sales tax on. If you did not pay sales tax on these online purchases, you would be required to report the amount on your state tax return to pay the use tax.
