Can you use an Invoice No. more than once. I bill multiple customers on the same day and want the invoice no. to be the same for each customer. For example, 051124 ???

I'm glad to help with assigning invoice numbers to multiple customers on the same day in QuickBooks Online (QBO), Kealy. 

When creating an invoice in QuickBooks Online, it's not possible to use the same invoice number more than once.

If you need to create invoices for multiple customers, and you need a uniform identifier like 051124, you can consider adding a unique suffix or prefix to differentiate the invoices while keeping part of the number consistent with your invoices for that day. For instance, 051124-01, 051124-02, etc. 

If you want to create visually appealing invoice forms, you can refer with this article on how to do it. Customize invoices, estimates, and sales receipts in QuickBooks Online.

If a customer needs to make a payment on their invoice, you can easily receive and record the payment to track your account balance.

If you have any additional concerns about invoices in QBO, please post them here in the community or reply to this post. I'm always here to help. Have a wonderful day!