Actual cost for costing sheet

Dear Experts,

   I want to ask if I take a percentage from COGM as a S&A EXP. so at period end closing we calculate overhead as actual cost but it's not because this is a standard cost if the overhead calculated is 400 but actual cost for S&A on cost center is 500 how can I reevaluate the orders with the difference 100 between the percentage taken and the actual expenses posted.

thanks,

Nassar