I'm not familiar with the CPO mechanics but are there 2 payments made?
1 for purchase on which CGT would be chargeable & 1 for compensation on which income tax would be chargeable?
Depends on whether or not it's in respect of a chargeable asset (eg not a PPR) and/or whether the recipient can claim a relief such as Retirement Relief.
Suppose the end of a person's back garden(family home) needed to be cpo'd for the Dart West. If the home was being sold there would be no cgt. CPO compensation is calculated on the current value of the land. It seems that the owner would be at a loss if he/she had to pay 33% of any compensation to Revenue.