Despite your best efforts, there will always be customers who fall behind in making payments, often two or three months behind. If you are unsuccessful in collecting a long overdue account, turn it over to a collection agency, preferably the kind that is paid based on a percentage of the money it recoups for you. Just as sales people tend to be more productive when paid on commission, collections agencies will be motivated to work harder for you when their fee is based money they get. You may still not get all the money owed your business, but you will get some of it. In addition, the agency approach can save you both time and money when compared to internal collections efforts, and the fee can be written off as a business expense.