October 20, 2022

Mississippi Medicaid: Provider validation process change

Mississippi Division of Medicaid (DOM) is transitioning to a new Medicaid Management Information System (MMIS). Therefore, starting Oct. 3, 2022, UnitedHealthcare Community Plan of Mississippi will require claims include the following for all providers listed:

  • NPI number; and
  • Taxonomy code

This new process will be required for both MississippiCAN and CHIP claims effective Oct. 3, 2022.

Due to logistics, during the initial 45 days of this new process all claims will be entered into our payment system and a denial will be generated. You’ll have 90 days from notice of denial to resubmit the claim rather than maintain the original timely filing guidelines. This was unavoidable; however, UnitedHealthcare will work with you to ensure that any denied claims can be remediated as quickly as possible.

Claim validation overview

  • Claims must include a valid NPI number for all required fields and the associated taxonomy code
  • Claim validation is not complete until a 1-to-1 match is identified through NPI review against the state provider file
    • This will include validation of every NPI number submitted on a claim with their associated taxonomy codes and, if multiple locations, through the use of the ZIP code (billing and servicing providers)
  • Tax ID numbers are on the claim, but not used to match the state file
  • If we can’t find an NPI match on the state file or if the Medicaid Provider ID number associated with that NPI is terminated, the claim will be rejected
  • If the claim is rejected, a provider still maintains their timely filing standard of 180 days and can resubmit their claims as if they are new
  • If you have questions regarding your rejection and are unsure of what is incorrect, contact Provider Services at 877-743-8734
  • If there is an issue with how your practice/provider is registered with the state, you will need to contact Gainwell at 800-884-3222

Claim submission resources

Go to to:

  • View and submit claims
  • View, submit and flag reconsiderations
  • Submit information on pended claims
  • Find confirmations and access letters, remittance advice and reimbursement policies

Process change background

  • DOM’s new MMIS is called Medicaid Enterprise System Assistance (MESA) developed by Gainwell Technologies
  • On June 1, 2022, DOM began issuing new Medicaid Provider ID numbers based on each provider’s NPI and taxonomy code
  • If necessary, the state assigned separate Medicaid Provider ID numbers where the same provider under the same taxonomy code has a separate servicing location
  • All providers should have received written notification from Gainwell confirming their Medicaid Provider ID number
  • If you did not receive notification of your new Medicaid Provider ID number, please contact DOM or Gainwell directly


Go to for more information or contact Provider Services at 800-557-9933.

Finding news icon

Discover more news

Personalized news icon

Get personalized news