A Receipt is created each time a deposit is taken or a credit card transaction is processed. If you are setup to use online processing of deposits, then 'receipts' will be automatically issued against the booking in the amount specified in the deposit. Clicking on the Receipt link shows Receipt Details, including an authorization and transaction ID when using a credit card gateway with the POS Module.
If you wish to use the features for adding Receipts – both credits and debits – to bookings, then make sure you upgrade to the Channel Management Tool Pro product. To see if this upgrade is right for you, see: http://www.bookingcenter.com/products/management_tool_pro.html and then contact BookingCenter to upgrade. In addition to offering the capability for managing credits and debits, the Channel Management Tool Pro provides a comprehensive Letters feature to allow unlimited customized communication – via printer, email, fax, or .pdf – for sending correspondence to Guests associated with bookings, as well as a full suite of Reports to better manage the system.