The High Balance report is only used for clients using MyCard (the integrated credit card processing for MyPMS). See MyCard

The High Balance Report brings to the attention of the management which bookings may need an additional or increased authorization amount or need a payment taken. Effectively, it tells management to 'watch out' for charges that may exceed authorized amount.

The report displays active Individual and Group Bookings with folio balances which have exceeded or are reaching the amount authorized at check in by a percentage you enter.. For example, all folio balances that have reached 90% of the authorized amount on the credit card. 

More information on Authorizations:

To run a High Balance Report:
High Balance Report displays the following information: