I am an online company and Amazon is my customer. I sell products and provide and invoice to the customer to pay. In the end Amazon charges an Amazon seller fee which is deducted once I receive payment from the customer. For example the invoice the customer pays would be 10. Amazon deducts 15% when I receive it in its entirety.

Would I classify the Amazon fees under costs of goods sold? And do I have to put this item on my invoices even though the customer would never see this deducted price? Or can I simply input it as a credit memo and deduct it from my gross amount as one big memo as a whole?

Please advise.

Regards

You seem to be mixing apples and oranges. It does not sound like Amazon is buying from you. You are using Amazon as a selling platform, for a fee, right?
Selling fees go under 'selling fees' (along with other overhead however you want to name them) under 'expenses' in your own business bookkeeping. The customer has nothing to do with it.

Since you seem confused about starting out, just do a cash basis accounting of Income and Expenses. So easy. No debits and credits.