Pension payments and CGT

I've read that making pension payments in the same year as the sale of a property can reduce the amount of CGT due, and I just want to check this is correct. Let's say I have an income of £50,270 in the 2024/25 tax year. I sell a property and calculate that I have a £20,000 capital gain. As I'm a higher rate taxpayer, I would need to pay CGT at 24%. If I make a pension contribution (relief at source) of £20,000 in the same tax year, does that mean I would pay CGT at 18%? From what I've read, pension contributions extend the basic rate tax band, so in the above example, the basic rate would increase by £20,000, therefore impacting the amount of CGT due - have I understood this correctly? A final question about this, if I enter the pension contribution into my self-assessment tax return, will the CGT due be adjusted accordingly, or would I need to contact HMRC separately about this?

Hi,
As pension payments extend your basic rate band, then this would mean more of your income is taxable at the lower rate and this includes the capital gains income. The tax return will reflect this once you enter the pension contribution.
Thank you.