how to process an overpayment by a client who has been invoiced a lesser amount?

Hi BTS13, you can record the full $187 payment via + Create > Receive payment, select the client/customer, and apply it to the $142.50 invoice. QuickBooks automatically creates a $44.50 credit for the excess amount.

You can then apply this credit to an existing or future invoice, or issue a refund. Refer to this article for detailed steps: Handle a customer credit or overpayment in QuickBooks Online.

If you have any other questions about QuickBooks, we're here to help.