Posted: Tue Nov 7, 2023 2:50pm
There is no 90 in 180 or restrictions on EU members. However, if he stays more than 183 days he becomes a tax resident in Spain regardless of whether he is registered or not. To stay over the 90 days he should register on the Non Spanish EU citizens residing in Spain as a non resident up to 183 days. Once they go over that they become fiscal residents.
Now, in the real world, there are no checks made on EU citizens entering Spain therefore the only way he would be caught would be if he registered his stay or was asked for proof of flights. That ain't gonna happen and didn't happen to the Brits when we were in the EU. It's only now passports are being stamped that a check can be made.
Officially, no he can't stay more than 183 days in any one calendar year. Realistically he can do what he wants unless he gets picked up for an offence.