I have taken on a new client for the first time. They are a very small company structured as a C Corp.

They do about 800K a year in sales and hold about 50-60k in inventory.  I took over last year and had them do an inventory count at year end. what I found is they had a lot of negative inventory at the time. I am now preparing the tax return and my COGS calculation for the 1125-A is $6,017 short of what is on the Income statement.  How would this be handled when doing the tax return?