Log in links for this page

  • This page, Electronic Data Interchange FAQ, is   offered by
  • MassHealth

Electronic Data Interchange FAQ

Frequently asked questions (FAQ) for MassHealth providers using the Electronic Data Interchange (EDI).

Table of Contents

What is EDI?

EDI stands for Electronic Data Interchange. It’s a process that facilitates the exchange of electronic HIPAA compliant files. EDI is the industry standard term for electronic transactions.

Where can I get the EDI specifications for my MassHealth electronic claims?

The EDI specifications for MassHealth electronic claims are based on the following documents.

An Implementation Guide is available for each HIPAA transaction that MassHealth supports. It is accompanied by a MassHealth Companion Guide and the appropriate submission instructions to guide providers on the submission of transactions to MassHealth.

How do I know that my ASC-X12 HIPAA transaction file (for example, 837 claims file) was received and accepted by MassHealth?

MassHealth will generate a 999 acknowledgement. The 999 will show the number of transaction sets received in your file and their status. A status of "A" in IK501 means that the transaction set was accepted; a status of "R" means that the transaction set was rejected. The AK9 segment shows the overall compliance of the file; in addition to statuses “A” and “R”, it may include a status of “P” in AK901. This means that the transaction was partially accepted. Only rejected transactions need to be corrected and resubmitted.

Verifying that a 999 is downloaded and reviewed for each submitted file is the responsibility of the submitter. The 999 should be downloaded from the Provider Online Service Center (POSC). Providers can also get a 999 by using the MassHealth connectivity submission method.

Submitters can use the industry standard, Simple Object Access Protocol (SOAP)/Web Services Description Language (WSDL), or HyperText Transfer Protocol (HTTP) Multipurpose Internet Mail Extensions (MIME) Multipart Web service to support the submission of transactions using MassHealth’s point-to-point connectivity method.

The 999 should be available for download no later than one business day after receipt of your file (24 hours). If you cannot download a 999 within that time frame or are having technical issues with the 999, contact the MassHealth EDI team at edi@mahealth.net.

  • Within 2 to 24 hours after submitting a HIPAA transaction, MassHealth will generate a 999 acknowledgment file if the 276 passes pre-compliance.
  • The 999 will show the number of transaction sets received in the file and their status.
    • The AK9 segment will give the overall compliance of the file.
    • The IK501 data element will give a status of the transaction set.
  • Providers must download and review the 999 using the same method the transaction was submitted to MassHealth (for example, the POSC or MassHealth point-to-point connectivity method).
    • A status of “A” in the AK901 means that the file was accepted.
    • A status of “R” in the AK901 means that the file was rejected.
    • A status of “P” in the AK901 means that the file was partially accepted.
    • A status of “R” in the IK501 means that the transaction set was rejected.
  • If the file was rejected or partially rejected, providers must correct the errors and resubmit the file.
  • Please ensure that your transaction aligns with the ASCX12 IG, MassHealth HIPAA Companion Guide, MassHealth billing instructions, and any agency guidance that is issued (for example, relevant provider bulletins).
  • Contact EDI@MAHealth.net for assistance in reading the 999 file or correcting errors.

What is a 999?

The 999 is a HIPAA-defined acknowledgement transaction that indicates the receipt of the transaction.  It contains the status of each functional group in the EDI X12 File submitted.

I didn't receive a 999. What do I do?

If you haven't received a 999 within 24 hours after submission of your 270, 276, or 837 Professional or Institutional file, email EDI@MAHealth.net with your submission tracking number to ask about the status.

How do I interpret 999-transaction information?

MassHealth has created a helpful billing tips flier to explain how to read your 999. For more information, you can review the 999 Transaction Implementation Guide, the HIPAA regulations, and implementation guides at http://www.wpc-edi.com.

Additional Resources

What documents should I use to find out how to submit healthcare transactions to MassHealth?

Use the Companion Guides that are specific to your transaction type (i.e., 270/271, 276/277, 820, 834 Inbound, 834 Outbound, 837I, and 837P).

If you want to submit transactions using MassHealth’s Connectivity Method, refer to the New MassHealth Connectivity Method Frequently Asked Questions (FAQ) for instructions.

If you have any questions about how to submit transactions, please contact us at EDI@mahealth.net

What HIPAA transactions does MassHealth support in the MMIS?

The following transactions are supported via the POSC and the MassHealth Connectivity method:

  • 270/271: Health Care Eligibility/Benefit Inquiry and Information Response
  • 276/277: Health Care Claim Status Request and Response
  • 820: Health Care Premium Payment
  • 834: Health Care Benefit Enrollment and Maintenance Outbound
  • 835: Health Care Payment/Advice
  • 837I: Health Care Claim: Institutional
  • 837P: Health Care Claim: Professional

What is a companion guide, and how can I get one?

A companion guide is used with the ASC X12 HIPAA Implementation Guide. It details a specific payer’s requirements necessary to process the HIPAA transaction within their system.

For more information and to get copies of the MassHealth Companion Guides, please visit the MassHealth HIPAA Companion Guides page.

What is a MassHealth Trading Partner Agreement, and do I need one?

A Trading Partner Agreement (TPA) is an agreement between the covered entities (HIPAA Regulations: 45 CFR Part 162.915) that are engaged in EDI transactions. TPAs specify the rules and responsibilities of each party involved in the transaction in addition to indicating requirements such as communications and financial arrangements (e.g., which entity is responsible for telecom costs).

All fully participating MassHealth providers who use HIPAA transactions are required to complete and submit a TPA.

Additional Resources

What do I need to do to make changes to my 835-transaction setup?

To receive the 835 transaction, connect directly to MassHealth systems or the Provider Online Service Center (POSC). If you need to change who receives the 835 transaction, contact us at EDI@mahealth.net.

What documents should I have available to successfully review the processing of my 835 transaction?

The management of your 835 transaction processing will be specific to your organization. Your IT staff may process the 835 file and use it for posting, or you may be responsible for interpreting claim results.

The following reference tools are available to successfully manage your 835 transaction processing. Depending on how your organization manages the 835 processing, you may need to have a copy of the following documents that are specific to your transaction type:

Download the MassHealth Companion Guides at  MassHealth HIPAA Companion Guides | Mass.gov.

Additional Resources

Contact   for Electronic Data Interchange FAQ

Date published: March 13, 2024

Help Us Improve Mass.gov  with your feedback

Please do not include personal or contact information.