Where can I find Unfulfillable Inventory Return fee report?

Sorry for asking such a simple question, I did a search in this sub and couldn’t find a direct answer.

I sell on Amazon CA and usually have unfulfillable inventory set to “dispose”. I recently tried recallinh some unfulfillable inventory, instead of disposing. Each unit came individually in a pretty large amazon box with the labels back to my address. My product is pretty cheap – I’m worried that doing this is cost prohibitive. How do I find out the fee’s associated with Amazon sending me back unfulfillable FBA inventory, vs disposing it. Surely they are charging me for the return labels.. to be clear this is all FBA.

Thank you in advance!🙂