This applies if the letter ever actually arrives at the post office.  If the address is not a postal address but a Cadastral address then it cannot be delivered.
My adjuntament tell me they are not permitted to use an AP address on your Padron and my Gestor tells me that DGT will not accept one.  Therefor, one is stuffed.
Regarding BASE I made repeated visits to the offices in Amposta and Tortosa over a period of five years or more informing them of my postal address each time.  They finally got it right last year but this year I've had to request the bills by email.
Although I love Spain, the admin is a total joke.