The primary CPT code should be billed as the first service line on the claim. Additional services(s) should be billed on subsequent lines with modifier 51 appended, as appropriate. This rule applies to multiple surgeries, and multiple births.

When processing claims with an appended 51 modifier, the Idaho Medicaid Management Information System (MMIS) will only consider paid lines as the primary surgical procedure. What does this mean? If the primary service is denied for any reason, the system will look at the secondary service billed, and ignore the modifier 51 designation in order to process the services.

Additionally, the MMIS reviews the billed amount of services to help determine the order in which services should be priced. If the primary CPT code and secondary CPT code are the same billed amount, the services should be billed in a manner that differentiates the primary service and secondary service, in addition to the 51 modifier.

For more information relating to reimbursement or billing guidelines for modifier 51, please refer to the article titled, Medicaid Program Integrity Unit, Reimbursement Reminder for Physicians and Mid-level Providers published in the December 2018 MedicAide Newsletter.