I disagree that in-house is best. As an AC biller, we get rejections and work them in 24-48 hours from submission. Factually, no practice can do it all, and most of the AC users that come looking have either gotten in a pickle on their own, are being held hostage by either an in-house or outside biller, or are getting bled dry by a biller. The reality is that when you do a reality check on your in-house billing costs, (truly tracking your expenses and costs) you're better off outsourcing. And losing 20% of your collections? No way.