Working in UK as PAYE employee but living in Spain

Hi I am thinking about taking a job with a UK employer as a PAYE employee, I am planning (after seeking legal advice) on filing tax returns in both the UK and Spain. i was wondering what my position would be regarding my current NI contributions in the UK, as I will be in both countries for more than 100 days each. I will visit the UK to see clients and hold workshops and meetings and the remainder of the time work remotely. Is there anything I should look out for particularly regarding Ni contributions ? Thanks in advance

Hi claudio
If you are resident in Spain, then you will need to approach the authorities in Spain regarding a liability decision.
Generally you pay National Insurance where you work.
When you work in more than one country, then the Social Security authorities in the country where you live need to make a determination of where you are liable to pay.
If they determine you should be paying in Spain, then they can provide you with an A1, exempting you from paying in the UK.
Thank you.