Yes it is a tax on unsold inventory. If I spend $100 on inventory, my business has $100 less cash. IRS rules do not allow my business to write off that cost until the goods are sold (COGS). If I do not sell that inventory, the IRS treats the unsold physical inventory the same as $100 cash for tax purposes, however my $100 is gone and I have no customers, so unless I destroy my inventory, I have to come up with tax payments for $100 I already spent. I've witnessed retailers smashing mass amounts of merchandise in compactors to avoid taxes on sunk cost. Some publishers have incinerated train loads of books for the same reason. Unsold inventory is a liability... Regardless of what the IRS says, inventory isn't worth anything until someone pays you for it, and you can never be sure if anyone will pay you for it or exactly what the price will be until the transaction occurs.