How to record a cashback bonus I received from my business bank?

Thank you for joining us here in the Community, @Jim1954. I can give you further information on how to categorise cashback bonus in QuickBooks Self-Employed.
 

The cashback bonus you get from your business bank account is usually not part of the business's income. You can categorise the downloaded transaction as personal.
 

I'd also suggest referring to your accountant for further clarification and additional information. They'll be able to share further information as to when you can consider some cashback bonuses as part of your business income.
 

Here's how to manually add transactions in QuickBooks Self Employed:
 

1. Go to the Transaction menu and select Add Transaction.
2. Enter the amount and a description.
3. Select the Select a category menu. Select the category to organise your transaction. 
4. If you have a receipt, you can drag and drop it onto the form.
5. Then, select Save.
    

You can also check this article on how to categorise money transfers in QuickBooks Self-Employed. 
 

If you have a follow-up question about recording cashback bonus transactions in QuickBooks Self-Employed, I'm always here to help. Have a wonderful day!