FIFO and LIFO cost items may not be used on a work in process work order.

AI generated answer (using internal Slack threads):

Based on the conversations, it appears that FIFO (First-In, First-Out) costing method is not compatible with WIP/Routings in NetSuite. This means that FIFO and LIFO (Last-In, First-Out) cost items may not be used on a work in process work order. In terms of inventory management, FIFO can be used for cost of goods sold (COGS) even if you don't want to track it to the inventory level. However, if you want to ensure FIFO works for physical inventory as well, you must use lot numberings. This implies that you can sort the inventory by the price paid for it, but not based on how old the inventory is. If there are errors in the FIFO costed items that were incorrectly received and billed at the wrong costs, and the periods are already closed and cannot be re-opened, the cleanest way to fix it is through the Inventory Worksheet. However, this would only fix the on-hand inventory and not the actual cost related to the negative quantity. If the items have already been sold, the Inventory Worksheet would reset all the FIFO cost layers. ****** Disclaimer: This response was generated by an artificial intelligence assistant based on previous conversations from multiple Slack channels, and may contain inaccuracies or mistakes. ******