Rejection: Unknown/Invalid Payer (RC51)
What happened: Based on the payer name, payer ID, and address, we could either not determine who should be receiving the claim or the payer is not on our Payer List: https://cms.officeally.com/Pages/ResourceCenter/PayerLists/PayerList.aspx
Resolution: Need to put a valid payer name?and payer ID on the claim.