Thought I'd mention some info that might be of use to anyone from Alicante region, if I share my first experience of spanish tax earlier this year.. Most in Alicante region (I think) will know this tax as 'SUMA Tax' (SUMA is a government body setup to administer and collect it). http://en.wikipedia.org/wiki/Suma_Gesti%C3%B3n_Tributaria
Like many others I know I just ignored it again, and again. and again and although they've never actually threatened me with anything, the outstanding bill gets higher and higher as interest is continually added on (fair enough and prob better than our red letters!).
Each SUMA bill/invoice has an final expiry date for payment, after which if you don't pay you get another one with interest added and another expiry date on, and so on..
The main SUMA office is in centre of Almoradi but they DONT accept any form of payment there! (I tried). So long as your bill is still in date you just hand it in (or send it) to your bank and pay it from there (assuming your bank is on their list - which is clearly marked on bottom of the bill - most of the big boys are on there anyway. If the final payment date has passed, the bank WONT be able to pay it. You'll have to either wait for a follow-up bill (remember it's going higher the longer you wait), or as I found, if you call into the SUMA office, they'll print you out a revised bill there and then... but then tell you to go to your bank to pay it (strange way to do it I thought).
They encourage you to use a gestion or similar in spain and deliberately give the impression you have no other choice but to do this. Same goes for anyone charging to fill in a form for you. I liken it to most UK institutions that now do their best to penalise anyone who deoesn't pay by direct debit (for example).
At least next year (about now actually) I'll recognise it soon as it comes, pay careful attention to the last payment date and ensure I get it paid beforehand. Hope this is useful to some and may even save you a pound or two! ;O)