Hired to collect old balances

Best answers
A physician has asked me to come in and help clean up old balances from the insurance company. I have been looking online for an acceptable rate to charge for this as obviously these will be the claims that take a lot more work.

All I can find online is that physicians who want this service should expect to pay a high percentage for this type of collections.

What is an acceptable amount to charge? I live in a state where charging a percentage based on collections is legal - I know that is isn't legal in some states.

Thank you,