Stand Alone Credit Memo
If you return an item and create a standalone credit memo instead of a return authorization, NetSuite adds the quantity back to inventory. However, the value of the item isn't credited to the Cost of Goods Sold (COGS) account of the item. Issuing a standalone credit memo for a return can result in inaccurate costing for the item.
Best Practice
Always use the return authorization process to return items to inventory to maintain accurate costing. When you use the return authorization process, NetSuite gets costing from the originating sales order or invoice. Then, creating the credit memo from the originating transaction retains the link for costing. For more information, see Customer Returns.