VAT Update is a free WHMCS addon module that helps changing the VAT tax rules for the new 2015 EU VAT legislation
VAT tax Data is obtained online from VIES so that it is always up to date
The module will change the Tax Rates in the WHMCS tax configuration for you. It is possible to review these rules in the standard WHMCS Tax Rules page
As well, VATUpdate gives the option to update prices of client's products so that the VAT difference is assumed as a cost/benefit to the company and the client keeps paying the same amount each month. This is specially handy in the case of subscriptions where having the client changing the paypal subscription may not be worth or more difficult than assuming the price differences