US Sales Tax - you think EU VAT is tricky?
I'm UK based but have been working with various US online shops for years and their approach varies - some are going full-on with it, some hardly care, most are in between.
For those that do, it can be a world of pain:
- overall tax rate = city tax + state tax + federal tax (I think!)
- some zip codes span two cities, so you can't even tax purely by zip code
- in around half the states, shipping should not be taxed
- there are companies providing overall tax rates based on zip and city
- the list of records for every combination of zip and city for US + Canada is 700,000+
- oh, now you want to ship some shopping cart lines to one location and some to another?
- wait, now you want certain products to be tax exempt?
Ridiculously complex - I expect 100% of the tax is needed to pay the salaries of those administering the system.