Hi there, mat-juicylemonst.
Thank you for visiting the QuickBooks Community. I'll ensure you'll be routed to the right support to help you get what you need while running your business with QuickBooks Online.
There's no direct option in QuickBooks Online to get a banking letter to confirm that the account is legitimate. The downloaded data in QuickBooks Online depends on what your bank shares with us and how they're posted online. Also, the details and any authentication that are connected with banking information are from the Financial Institution. I recommend contacting your bank to ask for the mentioned letter. They'll have the tools to provide any add ons services.
You may refer to this article to view details on how you can check when QuickBooks deposits customer payments into your bank account: Find out when QuickBooks Payments deposits customer payments.
You can always get back to me in case you have other questions or concerns about any letters in QBO. I’m always around to help and back you. Have a good one!
