Multiple Tax options based on service location
This is an absolute must for any hosting provider operating in multiple locations. The current WHMCS tax system allows to set sales taxes system wide, based on one home base location basically. In the US for example, certain states charge tax on hosting services, and some do not. There is currently no way to charge tax on services you provide out of data centers in a state with taxes (Texas, for example), and those without, and set those rates accordingly. With just one taxable state you can jimmy-rig it, which we did, but we cannot sell service in any other state with taxes, until WHMCS updates the system to allow for multiple jurisdictions.
Larger providers require this and it may even stops smaller providers wishing to expand their operations in a proper legal tax-collecting manner. My guess is most hosting providers do not follow the tax laws properly, or this would have become a bigger stink. ;-(