Implementing Costing after Inventory and Manufacturing

Hello,

My client has implemented Inventory, Manufacturing, and Procurement without enabling the Costing module. Now, after 3 years, they wish to integrate Costing (Actual Costing).

From an implementation perspective, what is the recommended approach to enable Costing without generating costing distributions or journal entries for prior years? The objective is to begin costing only the current on-hand inventory as of the defined cut-off date, with no retroactive costing.

If we set the "First Period Open" value in the Cost Organization and Cost Book relationship page - for example, to Sep-25 - will the Costing module generate distributions and subsequent journal entries (via Create Accounting) only for the