How do I deal with insurance rejections I don't understand?

Those rejection codes can feel like a wall you keep walking into. You are not slow for finding them confusing. The system was built by many hands over many years, and it does not explain itself. Nearly everyone who does this work started out baffled by the same messages. The way through is not to understand every rejection at once. It is to build a small map, one code at a time. Keep a simple list of the rejections you hit most and what fixed each one. The next time it appears, you will already know the answer. Start today with the single rejection that shows up most often. Learn just that one well. Ask a coworker or call the payer and write down what they say. One solved problem becomes a tool you keep. Do that enough times and the wall turns into a door.