Hi,
Short answer is, unless you "Finish" the Production Order, any additional costs are collected in WIP and then when you do Finish it redistributes costs and updates the COGS accounts etc.
I don't recall what period it makes these adjustments in - probably the links other people have posted will explain that process as to which accounting period is impacted.
-Rob Jolliffe
President, Sabre Limited www.sabrelimited.com