Add a field so that customers tax ID can be stored along eith exemption status.
When a customer is Tax Exempt, we would like to be able to record their ID number for future reference, like when the state tax department comes to call.
You can add a customer custom field for tax exempt id and store it there, as well as add a popup or icon – check out the doc on custom fields:
Chip Reaves commented
Does RS have a tax exempt feature at all. I just had a customer call because our invoice included sales tax when they are exempt. None of our guys know for sure.