According to the ACA, 80% of all monies collected by a third party collection agency are done off of their letters, not their phone calls. Thus, it would make sense to use an agency that charges a flat fee for a series of written demands in lieu of subjecting your accounts to a costly percentage. The overall concept behind collecting money from delinquent customers/patients is changing their mental disposition. The best way to change their mental disposition is to involve a third party. Sadly, not all accounts are collectible. To maximize recovery, use an agency that offers a two step process. The first step is a series of written demands that charges you a flat fee per account. The accounts that are not collected from this first step would then be sent on to the second step, which is traditional collection efforts that involve a percentage. If you follow this process, you will recover the most money possible for minimal costs.