There are several reasons to register at the Town Hall.
-If you are going to buy a car
-If you apply for health service card, SIP( will be described later)
-If you want to vote for SMdS council
-If you are going to apply for Residencia ( will be described later)
-Town Hall will get allowance for health service.
Check your street address; you find it in the thread “Your street address” from April 29.
Take your passport and your house Contract or Deed/Escritura and visit the office to the left in the entrée hall in SMdS Town Hall/Ayuntamieto.
You can collect the Cerificado after about a week at the desk to the right. The Certificado lasts 6 months. If you need it after that time you just go to the reception and ask for an update.
The above worked last year, hope the rules haven’t changed. Good luck!