In this example, it's not the question of the rate - it's the question of which county gets credit for the 2% charged above the 4.75% state rate. I have to report (monthly) which tax due by county. The state takes care of distributing to the counties (and/or cities). If I used STC, it would all go to Forsythe County - even if the shipment went to Davidson. If I were audited, I'd get the fine or penalty.
And yes, I have a love/hate relationship with Amazon (love to hate them :-> ). I get a lot of orders through them as a 3rd-party seller in their marketplace. But they also compete directly against me on certain listings, and where they're not authorized by the manufacturer of the goods as a dealer. The manufacturers won't take them on - either because they like the revenue too, or because they're afraid to take them on.
Got it thanks. A compliant service cannot just go by zip. I write a lot of web services and this one definitely sounds like an interesting challenge. I think for such a service to keep up with all the tax changes and jurisdiction minutiae it would need to be crowd sourced. In order for such a crowd sourcing to be accurate (not sabotaged or sloppy) it would have to validate and reward the people who add the tax entries and write the 50+ automated filing add-ons.
Ideally it would be a cooperative effort by vendors who get to use the service as their reward while vendors who do not contribute would pay some of the upkeep. Although web service upkeep is getting cheaper all the time, the challenge here is the messy and inconsistent tax information and e-filing systems in the 50 states.
But a further complication is that simply copying Avalara's information is likely to violate their copyrights, and that would be hard to detect. But the biggest challenge is the filing not the calculation for each transaction