Hi Cathy
What costing method are you using? Is costing set per warehouse? Of the items that are currently in negative, how long have they been negative and how big is the jump in cost going to be?
Maybe the best would be to create a test database, and then adjust all stock to positive and see what the financial impact is.
The only real concern is always how incorrect the GP on sales has been whilst there has been negative stock kept at possibly wrong costs. This of course could mean that the actual Cost of Sales account could be over/under stated. You could of course, on the Goods Receipt document, change the G/L account on the rows to a separate account to see what the impact is when receipting back to positive.
Remember that the GP on sales documents historically cannot be changed, and that changes to costs now will affect the GP moving forward and perhaps this will be absorbed over a period of time dependent on the next purchase of the item and the quantities currently on hand.
The first principle to understand is how SAP handles an item that was in negative. This is based on Average Cost or FIFO and NOT Standard Cost. Here is an example:
On hand -10 Cost 10 Value -100
Purchase 20 Cost 11 Value 220
The entry will be as follows:
First 10:
Trading Stock Qty 10 Cost 10 Total 100
Price Diff.Acc (Qty 10) Cost 1 Total 10
Next 10:
Trading Stock Qty 10 Cost 11 Total 110
You will see that SAP will split the purchase posting to the G/L in order to adjust the negative stock first, then apply the full new cost to the positive quantity. So in effect the negative stock was sold at a cost of 10 and therefore the system must "reverse" this effect by posting at the same value.
Your COS entry in the G/L is now the 100 in COS and the 10 in Price Diff, effectively now showing the cost of 110 if you add the two together. There will be a timing difference as the negative 10 qty could have been sold over a long period and not necessarily in the same period as the purchase/receipt and subsequent Price Difference adjustment.
The next principle is understanding the Business Impact of blocking negative stock. The reasons many businesses allow negative stock are either bad stock discipline or delays in stock updates such as goods receipts. Some businesses opt to allow negative and fix stock later in order to prevent delays in selling, especially when they know the item is actually in stock and the onhands are incorrect.
So in short, consider if there would be any issues or processes preventing you from blocking negative stock.
Kind regards
Peter Juby