Hi George
Here's an extract from my book Making the Most of MYOB Software that should answer your question.
Cheers
Veechi
7.14 What if I receive a warning telling me that a credit note will value my inventory at less than zero? Sometimes, when you try to put a credit note through for inventory items, you get a message saying that ‘The purchase of this item would value your inventory at less than $0.00’.
If you see such a message, you won’t be able to record the credit note. This is because if you want to put a credit note through to reduce stock levels of that particular item down to zero, the credit note must equal the total value of stock on hand (based on historical average cost) for that stock item. However, prices are always changing, so it is highly probable that the unit cost per your supplier’s credit note is different to your average historical cost.
Enough of the whys and wherefores. What can you do about it? Here’s your workaround — it may seem a little awkward, but it does mean you can record the credit note and continue with your work?
Click Set Item Prices and then Avg Cost. Note the Average Cost for the item you are crediting — be specific to the last decimal point.
Return to your credit note, and use this Average Cost as the Price.
Note the Total Amount of this credit note and calculate the difference between this and the total on the credit note you have received. Then click Record.
Now you need to put through an adjustment for the difference. To do this, create a new purchase, click Layout and select Miscellaneous.
Use a cost of sales account as the Allocation Account, and write the credit note number in the Memo field. Remember to put a minus figure in the Amount column if you are doing a further credit adjustment.
With this complete you now either have two credit notes, or a credit note and a purchase. These two transactions together should add up to the value of the credit note that you were trying to record.
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Author of MYOB Software For Dummies, MYOB Certified Consultant, and author of Making the Most of MYOB Software
http://www.myob-help.com