Recording expenses/charges in Rentables is a two step process. First you record the charge. Later you record the actual payment of the charge. This is designed to mimic the typical workflow for a property manager.
Record the Charge
It's common to receive invoices or bills for owners mid-month. You will want to record these in Rentables as soon as you receive them (see How to record a charge). It will appear as an unpaid charge under the owner's account until you record payment.
Later when you receive rent, you can deduct the money for any previously recorded charges before paying the owner proceeds (see How to record payment of a charge).