Running a UK Ltd Company in Spain

Hello All

I came to Spain about 4 years ago and was spending a lot of time in London working also but got spanish residency December 2020 Just before Brexit. I freelance for London based companies and all my work is done remotely for the the UK. Anyhow when I applied for residency I mentioned this at city hall and they said I could put on my application that I was living on savings and buy private healthcare, I did also give over documents of registration of my UK Ltd company when I applied for residency also. Since then I have not been contacted by the Spanish tax authorities and not registered to pay tax here, although I have been here over 183 days in the years since registering (2021, 2022). If I register I will prob have to register as autonomo and be employed by my UK Ltd company (is this correct). Autonomo social security is ridiculous, something like 200EUR/month even if you're taking a salary of 700/month, I pay private healthcare so I dont need the healthcare part of it, and to receive a pension from it I need to be paying tax for 5 years in Spain I beleive, and I may not live here that long...

My question is - how would the tax authorities know I am here 183 days a year? Also why wpuld they check if I havent heard anything already? My earnings are pretty small (less than 40K a year) and all from UK companies going to my UK account.

Is it worth me registering for tax in Spain.

Thanks!

​​​​​​​Paul