I am advised by Revenue that the matter of whether the amount of pension being paid to the person concerned is correct is a matter in the first instance for the pension provider.
The tax credits allocated to the person concerned are, based on the information available to Revenue, correct.
If the person concerned wants to verify the correct tax has been deducted for any year, he can request a review of his overall tax position at the year end. The fastest and most efficient method to request a review is for the person concerned to register for Revenue's online service myAccount and to request the review online, on receipt of his P60, for the year in question.