Hi Ali,

You can add a reference number to a credit card payment during bill payment in QuickBooks Online (QBO).

Here’s how to do it in QBO:

1. Go to My apps, then select Expenses & Bills.
2. Select Bills.
3. In the Unpaid tab, find the bill you paid with your credit card.
4. Under the Action column, click the dropdown arrow for that bill and select Mark as paid. The Bill Payment page will open.
5. On the Bill Payment page, choose the vendor and the credit card account, then enter the transaction ID in the Ref no. field.
   
6. Click Save and close when everything is done.

The Bill Payment page also includes a Memo field, which you can use not only to record a reference number but also to add longer details.

If you have any additional questions, please feel free to reply to this thread.