Good to see you here in the Community, vivl2010.
QuickBooks Online lets you record a partial payment on an invoice. You can record the first payment that's due now by following the steps below.
- Click + New and choose Receive Payment.
- Select the name of the customer/project from the drop-down menu.
- Choose the Payment method and Payment date.
- Under Amount Received, enter the partial amount of the payment.
- From the Outstanding Transactions section, select the transactions you want to apply the payment to.
- You can either deposit the money to your current account or to the Undeposited Funds account.
- Hit Save and close.
You can follow the same steps when recording December's payment. I'm leaving you this write-up: Record invoice payments in QuickBooks Online. It contains information on how to record multiple payments in QuickBooks Online. Also, this will provide you steps on how to find customers' balances.
Please let me know if you have any other questions. I'm always here to help and provide you additional assistance. Have a wonderful day!