How to create an invoice for client to pay in 2 installments?

Great question you have there, @bonnyspeaks.

You can create a regular invoice and enter the amount your customer pays you. For example, you invoice your customer for $100 and they pay you $50. When you receive the payment, enter the $50 amount they paid for that day.

Here’s how to do it in your QuickBooks Online (QBO) account:

1. Go to the + New menu and select Receive Payment.
2. Select your customer's name and invoice to apply the payment.
3. In the Amount Received field, enter the amount. 
4. Then select Save and close.

Let me also add this article that can guide you through the steps on how to let your customer pay their invoice online: Send online invoices in QuickBooks Online. This way, you no longer need to record the invoice payment manually.

Do get back to me if you have other follow-up questions in managing your invoices. I’ll be more than happy to help you out again. Have a great day