HCM Benefits- Tax type code to use for pre-tax amount

Hello ,,

We are currently setting up standards rates in the Benefits , to which we have to add 9% of taxes. That part will be handle by the elements on the payroll module side. Those elements are set up with tax type Code '' After Tax''

The question is , how should we be setting up our tax type code for the standard rates, if we should be putting them as Pre-Tax or After Tax ( same as the payroll elements) for the tax to be applied

If anyone has any hint or advice, please let me know

Thank You