CGT on cashless exercise of RSU

[CGA]

Hello,
My UK client works for a US quoted company and is given shares (RSU) as part of his salary. The tax on exercise (45% higher rate + 2% NIC ee + 13.8% NIC er) is funded by instantly selling 60.8% of his stock (cashless exercise).

As this is a disposal of shares does this need to be reported on the Capital Gains pages, although the gain is nil (same day sale)?
The client doesn't have any other gains to report for the tax year.

Thank you in advance for your input.