drug allergy testing to Medicare

I billed 99213-25, 3 units 95017, 20 units 95018. I am not getting paid for the 95018. The practice is in Illinois, NGS is our processor for Medicare. My denial remark is frequency, and number exceeds max. Yet I cannot find any documentation for limiting units amt for this code submission to Medicare. Any ideas?

re: drug allergy testing to Medicare

I'm not finding anything on the NGS website either, I tried the CMS website and found some documents. They're quite long and I'm not familiar with allergy testing so I don't know if they are relevant to you, but check out LCD ID L30471. Make sure you scroll down to the Associated Documents section near the bottom of the page and download the Billing & Coding Guidelines PDF. I hope something in there helps you.