What would the loss figure be

Client bought a Spanish property (holiday home) a few years ago for 400,000. He paid cash 50k and had a Spanish mortgage of 350k.

Last year the property had a value of just 200k so he decided to give the house up and default on the loan. The bank repossessed the house but didn't come after him for any further monies.

What would you show on the CGT pages?

 

Many thanks