No doubt, online sellers face a challenge when they have customers all over the country - almost every state has a different definition of who owes what. This is a big one for Amazon on sheer volume of sales, but smaller companies have to be constantly aware of what kind of operations they have going on from state to state, too. Otherwise, they could be racking up sales tax without even knowing it.

Some useful links…an audiocast on the subject here:

http://www.mfa-cpa.com/mfa-news-and-resources/thought-leadership/EcommerceSalesTax.mp3

and a white paper here:

http://www.mfa-cpa.com/mfa-news-and-resources/thought-leadership/ECommerceSalesTax-May08.pdf

Hope it’s helpful!