Why don “daily deal” sites list the tax that will be charged in their emails?
Probably because the tax to be charged often depends on how the merchant interprets the individual state’s tax laws and the deal site doesn’t control that. Realize that the terms of service for most daily deal sites specify that the merchant, and not the deal site, is actually issuing the deal (see Groupon’s terms at http://www.groupon.com/pages/mer…, specifically section 3.4). In some states – notably Massachusetts – the state has made it clear that sales tax is paid on the total amount actually paid by the coupon user, which includes the cost paid for the deal plus the net amount after the deal is applied. In other states – notably California – the state has indicated that it expects to collect sales tax on the full pre-discount amount. In many states, however, there’s no clear interpretation one way or the other just yet.
