Having just had dinner with a Spanish friend he seems to think that this is only an opportunity to admit to 'black money' purchases before a deadline.  (A bit like America had regarding Swiss bank accounts.)  In other words if your foreign assets are legitimate then there is nothing to declare but expect punitive treatment if they find stuff which you haven't confessed to which is hookie.  Expect the Spanish Inquisition!!! 
PS  Last I heard there were no forms available to fill in.  Perhaps they need to pay the printer in cash to get on with them.   ;)