I had shares in Spain which I sold in August 2019. Due to the double taxation agreement, I am supposed to pay my taxes in the UK. However, my fiscal residence was not updated in Spain, so the bank did a retention tax.
Under UK taxation, I shouldn't have paid because I don't reach the capital gain tax allowance. I requested the tax relief in Spain and they gave me back just a small part of the retention. I have to request the other part to HMRC.
Any idea on how I shall report this on the self-assessment?