1) "If the cryptos were acquired before getting the Spanish residency, the Spanish government would have zero say on it."Yeah, the global trend on crypto taxation isn't very encouraging.
And if this is okay for now, probably this avoidance loophole might close eventually.
But so far this is my takeaway from this discussion:
If the cryptos were acquired before getting the Spanish residency, the Spanish government would have zero say on it.
And if I only held the cryptos without selling, no reporting requirements.
And if I get a line of credit with crypto as collateral, no capital gains taxes.
And if you live in Madrid, you are not subject from Wealth Tax.
So you would be compliant.
If they were legally acquired, yes.
2) "And if I only held the cryptos without selling, no reporting requirements."
If they're held in a cold wallet (trezor, ledger, etc) in Spain, I don't think you're required to report them. However, if you exchange crypto to crypto, crypto to fiat, or deposit them into an exchange, you'll have to declare that.
3) "And if I get a line of credit with crypto as collateral, no capital gains taxes."
There's nothing about defi/lending/borrowing in Spanish law, however, it's a tricky situation. In order to get a loan, you'll have to deposit the crypto into either Celsius, Nexo, BlockFi, etc; if they're in one of those platforms, the taxman can ask them for your info and you also have to declare that you have the cryptos on the website. So yes, you'll be able to avoid capital gains taxes but taxman may now know you have X amount of crypto.
4) "And if you live in Madrid, you are not subject from Wealth Tax."
That's correct, however, that doesn't mean you don't have to do anything, if you have over 2M Eur, you'll have to declare it.