Postby AGoodman » Wed Aug 29, 2018 4:13 pm
Being tax resident in the UK would not prevent you also being tax resident in Spain. Also bear in mind that the Spanish residence rules are not just based on days - you can also be tax resident via having your centre of vital interests there and if you have spent nearly half a year there, and were resident there last year, I would have thought this was a very big risk.
The UK position is now just a formula - see RDR3.
If you have a home here and spent over 90 days here in recent years, you will need to do 121 days over the course of the UK tax year to be tax resident for the entire tax year. You can't qualify for the family tie on the back of adult children. There is no need to achieve the days by the end of the calendar year 2018 for UK purposes.
If you can't do that by 5 April 2019 then take a look at the 2nd Automatic test. Failing that, you are probably not UK resident but bear in mind what I said above - it may not help you anyway.