Campo, For the past couple of years it has only been possible to complete the 210 (non residents second home tax) on-line, If one is not registered with Hacienda, then the form can be downloaded and taken to your bank in Spain, where they are stamped and paid through your account.
Prior to that one was able to buy the forms in an Estanco.
As for the renta (income tax return for residents) my gestor completes the return on-line, prints out the forms and again I pay them over the counter at my bank, with the money being transferred from my account