Answered: NEC PSC: Expenses recovered through audit and actual costs?

The expenses set out in Contract Data Parts 1 and 2 determine 'what' expenses are recoverable, including the amounts, where applicable, such as mileage allowance for travel by car.

When you say 'rates in the ... data or the actual receipted expense' I presume that an amount is expressly stated for a particular type of expense in the Contract Data, with a corresponding actual amount incurred against this.  The amount paid would depend upon whether the Contract Data stated an 'actual amount', such as car mileage allowance, in which case that would be used as the basis for an expenses calculation.  Similarly you would pay for staff at the staff rate stated in the Contract Data, rather than the actual cost.  Likewise under ECC main option E you would assess the cost of Equipment using the rates in Contract Data Part 2, where applicable.

Clause 52.2 requires an auditable trail of evidence to be kept and maintained so that the requirement of 'expenses properly spent' at clause 50.3, can be demonstrated and confirmed, for the purposes of a payment assessment.  This clause, relating to expenses, applies to all the main PSC options.