FBA return costs

Hi all, can you help me please? Do Amazon charge me as a the seller for postage from the customer back to Amazon for FBA returns? I have looked on google search and I still don’t know the answer. I know they charge me a fee of some sort, but do they charge postage on top of that please? and if they do, where can I see how much that is? sorry if this sounds like a basic question, but i don’t know where to look. Thanks