subject: Modifier 90 – Signup for a One Stop Website [print this page] Whether it's AMA coding modifier 90 or any other modifier, you will often find yourself in difficult situations when it comes to these modifiers.
You should append modifier 90 if you are an independent lab billing for a test that you didn't carry out in-house. Modifier 90 points to the payer that a party other than you, the reporting lab, carried out a particular procedure. In essence, you are billing on behalf of the party that carried out the service.
Sometimes you may encounter questions pertaining to modifier 90. "When we send across specimens to the lab, we report the test with modifier -90 and add a little percentage to the charge amount in order to cover our expenses for clinic. One of our family physicians think this is illegal and wants to alter the way we do business. Is he right are we coding right?
The answer is that both you and your doctor may be right. From a coding point of view, you are correct that modifier -90 represents a test that an outside lab, and not an office, performs.
However, your doctor correctly points out that you may not be reporting these services correctly. If the lab submits the same test code that you do, you're double-billing the service.
In order to avoid duplicate coding, you should have a written pass-through-billing pact with the laboratory. If both parties agree to the pact, you'd code for laboratory's tests using modifier -90. It indicates that you're reporting a test that an outside laboratory carried out.
For more on AMA coding modifier 90, sign up for a one-stop medical coding website. Such a site provides you with modifier coding survival guides, which feature chapter-wise information on modifiers.
