In standard SAP, whenever a customer is dunned for an open item, the dunning level is not only maintained on the open item, but also on the customer.
A typical scenario would be that when the customer does not pay his bills within say 30 days, the customer receives a dunning letter, raising the open item to level 1. Then after another say 20 days, the customer receives a reminder, raising to level 2 etc.
As said, the indicator for level 1 and level 2 are both maintained on the open item and on the customer.
But... when the customer pays, standard SAP will clear the open item, but the indicator on customer level will not be deleted, nor will it be redetermined.
This can lead to an unclear situation, as the customer can have dunning level 2 for instance on the customer master, whilst not having any open items with a dunning state.
Ideally, clearing a posting should redetermine the customer's dunning level just like the dunning process does.
Alternatively, a periodic redetermination of the dunning level of the customers could be the solution.
SAP chose for the latter with note 1420146 - RFCORR15: Resetting dunning level in master record
This note delivers a report "RFCORR15" which will redetermine the customer's current dunning level and last dunning notice based on the customer's open items. When all items are cleared, the dunning level on the customer master will be cleared.
Simply download and implement the note using transaction SNOTE, create a proper variant for the report and schedule it periodically.
The dunning information on your customer master will be back up to date.
Note that running the program in test mode will give you a simulation on what adjustments would be made by the program.