Posted: Fri Jan 24, 2020 1:24pm
I was an offshore worker!
Assuming he's a UK PAYE employee then he will have no option but to pay tax in UK, those are HMRC rules and neither Spanish residency nor numbers of days in or out of the country override them.
He will have to complete Spanish tax returns but the tax he's paid in UK will be offset against what he's paid in UK. Note that his overall tax burden will go up (possibly significantly) because the allowances in Spain are not as generous as in UK. this is just a fact of life and not as some seem to think some form of double taxation.
As UK employee paying NI he will be entitled to a Workers S1 which will cover your health care in Spain in this case though it's issued by HMRC not DWP and will be renewable annually on it's anniversary for as long as he continues to work and pay NI.
In the circumstances the only point of a 'Spain Individual' will be to get interest on UK savings and investments paid net of UK tax but they will still have to be declared in Spain.