Overdue CGT on UK property letter - but made a loss

Hello, I sold a property in 2022 and made a CGT loss. I reported this on my 22/23 Self Assessment, but didn't complete a CGT on UK property return as I'd made a loss. However, I've received a letter from HMRC saying I need to fill in a CGT property return on they'll make a determination for tax they thinks is owed. They presume I made a profit. How do I let HMRC know that I made a loss and no tax is due? I've heard that letters take months to be processed. I also couldn't fill in a property CGT form if I tried, as it's impossible if you've already submitted your self assessment for that year. I'm worried I'll be sent a determination in error without the ability to communicate the details to HMRC. Many thanks for your help.

Hi
You will need to reply to the letter you received to avoid any determination. A specialist team will have issued this and their address is on the front of the letter to ensure it is not linked in with other general HMRC post for a speedy reply.