Pool of actual cost of shares in Section 104 holding from work award scheme?

Hi all I'm going around in circles and pulling my hair out on this.....! My partner was has some shares that she acquired through an employers share award scheme, some in 2018 and some in 2019. She sold a small amount in 2023 and then again in 2024, and I'm trying to calculate how much tax is due on them. I have found the examples for how to calculate shares held and sold within a Section 104 holding. However, what I am really struggling to establish is how to calculate the "Pool of actual cost" of the shares. For all the examples I have found you need to number of shares purchased and the cost of the transaction. However, if they were acquired through an employers share incentive scheme, how do we do this? I know the share price (value) at the dates of each of the awards, and at the time of the awards she sold a percentage of the shares awarded to pay the amount of Income Tax and NI that it was subject to, which was calculated by the employer at the time of the award and dealt with by them prior, after which she received the remaining unsold shares. However, they were not actually bought for a price, so I don't know what figures to use to determined the Pool of actual cost. Do I use the share price from the time of the award from the documentation we have? Or is the Pool of actual cost zero?! When I googled it one result came back saying that I needed to take the total amount of Income Tax paid from the transaction as the Pool of actual cost for each award. The example on the HMRC website HS284 Example 3 2024 helps you to calculate the 'chargable gain', but without knowing how to determine the Pool of actual cost I can't use the formula! Is anyone able to help please? I can't find any information that helps me for when the shares were not just purchased and were acquired through a work scheme! Thank you!

Hi,
You would need to check with the company/employer to see what price was paid for the shares.
Thank you.