[BorgHunter]

This is one of those "it depends on the state" questions. In general, a seller is going to calculate and remit tax based on the delivery address, but the laws are actually a bit more complicated than that. chasil, who lives in Illinois but is close to Iowa, might start having packages delivered to a P.O. Box in Iowa, for example. However, legally speaking, s/he must still pay Illinois use tax on that item provided it is "for use or consumption in Illinois" and less than the current Illinois use tax rate of 6.25% was collected originally. See http://www.revenue.state.il.us/Individuals/FAQs-Use-Tax.htm

Practically speaking, of course, few people keep detailed enough records to even calculate the correct use tax owed at the end of the year, and any tax that might have been owed goes uncollected and unnoticed. Which is the problem that led to this Supreme Court case in the first place.

[chasil]

One particular question is my use of Page Plus, my phone carrier. It was the first Verizon MVNO to get 4g.

I was on an automatic payment with them, and they announced that they were adding 911 taxes.

I canceled the automatic payment and started getting refills at pincheap.com (a dealer with no presence in either Iowa or Illinois), avoiding both sales tax and the 911 tax.

There is no "delivery" of any physical product, so I wonder if the tax status of that arrangement changes.

[vanadium]

It's for this reason Illinois residents don't buy a car in Wisconsin or another neighboring state with a more advantageous tax structure; you'll get nailed post-haste.

But if you're driving up to buy a few cases of New Glarus beer, chances are you're vastly unlikely (at or nearing 0%) that you'd be held to account for that purchase for Illinois tax purposes.