Implications of changing TAX rate on Live Site

Question

What would the implications be on changing the TAX rate on a live site environment?

The site has the correct rates setup, and all products are set to the correct tax rate, however the rate is set to 0.00 (unknown reasons why).

All prices on products are added and are the INCLUSIVE of TAX price.

What would happen if the rate is for example, changed to 20.00 (20%)?

Would the price still be correct on the product, as it has the INC TAX price already added and Magento would calculate this correctly?

Or would there be other complications?

Answer 1

The prices should be correct after your change the tax settings. Just remember to rebuild your price index (you can rebuild them all just to make sure).
The only problem I see (and I don't have a fix for it) is the fact that for the orders that were placed when the tax was 0.00% will still appear as having 0 tax.