Here in Spain the Tax Agency is, believe it or not, the most respected of government services. Given said agency is in receipt of ALL your bank details, you press a button and it completes your tax return. If you are owed money it takes about 5 days to receive it. If you owe money you have months to pay. I have to add overseas income and it recalculates things. I paid €45 for an accountant to check everything and she found a big error on my last ever employer details.
Also married couples can decide to be taxed separately or together.