Hi Lisa,
Your spouse would take 50% of the disposal value and deduct 50% of the acquisition cost when you acquired the property, as well as 50% of the Fees, such as solicitors fees, estate agent fees. This will give your spouse a capital gain.
If the property became your spouses main residence from the date it was transferred to your wife until the date it was let, you work out the total number of months that the property was their main residence, plus a further 9 months, over the total number of months that you they owned their share of the property.
You have 60 days from the completion date, to report and pay the Capital Gains Tax, to avoid penalties and interest.
Have a look at the link below, which includes a calculator and links to the online capital gains service used to report and pay the Capital Gains Tax.
Capital Gains Tax
If you both have tax to pay, you will each need to create a capital gains account and report your individual gains separately.
Thank you.