This is quite common and if you take over the mortgage the builder has on your property you will save cost
But it not always a good...but often it is...eg with Polaris World if you do this and use the bank as your Spanish bank you will get a better deal than those who do not
They should offer you commercial terms perhaps with some interest only period
The main problem as I see it, as at 2008 ,is that , before regulations got tight, some of the banks financed developments which did not have 100% permits, although they were expected to be granted
So you may be able for example to get a ' builders mortgage' even though there is no Habitation Certificate .....the bank is taking you as the security and not the builder so the finer points do not matter too much......banks are in business to make money!
You may well get the HC
But no one should complete a purchase without a HC.....and all the other permits required
One way of making sure that you have a legal purchase is to get a mortgage from an independant bank.....they will not lend unless everything is OK.....so a bit of an indirect guarantee
The good thing about buying in Spain in 2008 [ besides the fact that you will get a good deal!!] is that . provided you are sensible, you can be assured that it will be a legal build....the Spanish Government is making sure that the ' cowboys days are over'