You should to do so. Spanish goberment does not care if you get the animals for free, but if you get any money, selling them, or charity ways, you have to pay for that
It is the same for me, you have not to pay me for my work, but if yuo do so, I have to declere my incomes, even when do do not have to pay for they.
But once I ve got your money, I have to declare it.
You got an a legal exit. if you make that PEPA will be a legal society, not to get money, they are call sociedad sin ánimo de lucro, wich is though to make not making money puorposes. So you should make PEPA as a sociedad sin animo de lucro
This society, get money for free, but have noy to get profites and have to dedicate the fonds obtained, in his onws objetives, as could be to get a better homes or betterway of livimg for abandonated animals.