automatically add VAT value to SUBSCRIPTION value for EU countries in PayPal

I sell my service on internet based on Subscription model. I use PayPal to in order to get the subscriptions from my clients. Based on the new EU financial requirements I have to charge different VAT value based on the country of residence of my EU clients. Basically I need for all my EU clients, at the checkout to add automatically the VAT value based on their country of residence, and if possible, in case they have valid VAT registration number, they should be able to enter that number so no VAT will be added to their subscription. Be advised : is for SUBSCRIPTION option, not for "Buy NOW" option. I do not own any script to comunicate wit PayPal's API. The "Subscribe" buttons are created by use of PayPal's website. May be we should create the script to comunicate with PayPal API. Is there anyone able to help me implement this feature ? Thank you.