At least in the case of Washington/Oregon, if you shop in Oregon and live in Washington, you are still required to pay sales tax as if you bought the items in Washington. I don't know anyone that does this, but I remember that the state used to run ads in the Vancouver, WA newspaper (right across the border from Oregon) reminding people of this and including a form to fill out and submit with your payment.

This is difficult, if not impossible, to inforce except for business expendatures and things that require licenses. Businesses are audited to see if they bought something, not inventory, in a state without sales tax. They are required to pay sales tax on the item. It's on the "use" tax portion of the B & O tax form.

The auditor collects sales tax on vehicles, etc. when they are licensed, if they are bought in a state without sales tax.

Jean....lives in Washington 14 miles from Oregon