If your private payors consistently lag on paying claims and fail to meet prompt pay law requirements, in most cases, you are due interest. New York, for example, pays interest at the greater of 12 percent per year or the state's corporate tax rate, according to the state's website. In Illinois, insurers must pay interest at the rate of 9 percent per year, the Illinois state website indicates. Good practice: You can fight back against insurance companies that are continually late in processing your claims with these three steps: 1. Prove your own timely filing. Send a printed copy of your electronic proof of timely filing. Most billing software programs can print out an electronic confirmation from the insurer saying it received the claim, including the date of receipt. This is an excellent form of proof that the payer received your claim and when. 2. Compose and send a letter stating the payer is violating prompt payment laws. Consider threatening legal action if you don't receive payment. 3. Contact your state's insurance department. If a payer is consistently slow in paying your claims, take the problem to an authoritative body. Tip: Most states employ consumer hotline numbers so you can contact the insurance department directly if you want to dispute whether your claim was paid on time. You should contact your insurance department if you feel your claim was not paid in a timely manner. Watch out: You'll most likely need to prove that you had "clean claims." Prompt pay law deadlines generally apply only to clean claims.