In Dynamics GP you can set a maximum write off amount for a customer on the Customer Maintenance Options card. (Cards | Customer, click options). This works great for controlling small writeoffs, little short pays, etc.
At some point though you’ll need to write off something larger. A great way to do this is to add a password to exceed the maximum write off. This is set in Receivables Setup.
At one time or another you’ll have write off’s and GP gives you lots of options.