Dunning is an important field in customer/ vendor master record in SAP FICO system. It reminds customers to pay bills on time. It has 4 levels and at each level system send message to customer.
In dunning, it is very important to assign dunning parameters to master data. That's how system gets to know how to dun a customer.
We can put a dun block too in the master data.
Dunning can be used to check secure customers in credit management.