Registration is online. To sign up, just follow the steps in the following link.
We recommend that you have ready the following information with you when signing up.
Built surface area of the house (An estimate is fine, but if in doubt, review your contract or sites like the Spanish property registry or Idealista).
Year the house was built (If in doubt, review your contract, sites like the Spanish property registry or Idealista, or contact the town hall).
If you have, your mortgage loan number (The 20-digit number identifying your mortgage can be found on payment receipts, your mortgage contract, or by contacting your bank).
You can sign up with your passport number, your NIE or your Spanish DNI.