Sacrificing car allowance into workplace pension

SOLVED

Hi

I have taken over payroll from a previous member of staff and there is one employee who has a monthly car allowance rather than a company car.  He sacrifices the monthly amount into his pension rather than be paid the money. That bit I understand.  My query is how it's been dealt with in payroll - the car allowance amount has been added to the ER pension contribution value on the pension tab.  It is not shown on his payslip as "car allowance" pay element and then a deduction for salary sacrifice for the same amount plus whatever additional percentage he sacrifices from his monthly wage (currently 9%).  Is this the correct way to deal with it or would the outcome be the same if I was to change it so it added his monthly car allowance to his payslip and then sacrificed it along with a further 9% as is his request?

I don't want to change how it's been treated all this time without understanding the implications.

Thanks