Vendors Invoices after Job is Costed - 8.03.305k

Most of our jobs are costed shortly after completion and the costs all
come through fine but we are finding some of our larger jobs that have
subcontracting and larger components, have invoices showing up after
our costing process is complete.

Due to the complexity of our products we do not always have a full list
of components and subcontracting prior to starting the job so it is
easy for these items to get missed.

Any suggestions on how to catch this extra cost so that we can update
our costing information?