Medical Billing Terms 0-9: EDI Codes (Transaction Codes) and Federal Rules

EDI codes are the numeric transaction codes (837P, 835, 270/271) that carry your claims, payments, and eligibility checks. This page defines them with other medical billing terms that start with a number. Each entry gives a plain definition, why it matters, an example, and an official source. MCM South Medical Billing Service, LLC works only in mental and behavioral health billing.

Last reviewed: October 10, 2026Sources linked at each term

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Billing Terms Glossary slide, Terms 0-9: EDI Codes - MCM South Medical Billing Service, LLC

Glossary pages

0-9A B C D E F G H I J K-L M N-O P Q-R S T U-V W-Z

On this page (13 terms)

1115 Waiver
270/271 Eligibility Transaction
276/277 Claim Status Transaction
277CA Claim Acknowledgment
278 Prior Authorization Transaction
42 CFR Part 2
60-Day Overpayment Rule
834 Enrollment Transaction
835 Electronic Remittance Advice
837I
837P
988 Suicide and Crisis Lifeline
999 Implementation Acknowledgment

How to use these EDI Codes definitions

Use this page as a quick reference for EDI Transaction Codes, from 1115 Waiver to 999 Implementation Acknowledgment. Each entry gives a plain definition, why it matters to a mental health practice, and an official source. When a rule changes by payer or state, the entry says so, so confirm EDI Transaction Codes details with the payer before you bill.

Checklist: put the edi codes definitions to work

Check the edi codes entries above before you send a claim that depends on them.
Share this edi codes page with front-desk and billing staff so everyone works from the same definitions.
When a payer letter mentions edi codes, find the matching entry and note the date you checked it.
Keep your edi codes notes next to your payer contracts, because a contract can define a term differently.
Ask the payer to confirm in writing how it applies edi codes before you change a workflow.
Train new staff on edi codes first, then move on to the rest of the glossary.
Log any edi codes question that comes up twice, then add the answer to your billing procedures.
Use the source links under the edi codes entries to confirm the current rule.
Print the edi codes entries you use most and keep them at the billing desk.

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1115 Waiver

Medicaid (state-specific)

Also called Section 1115 demonstration; Medicaid waiver

Definition: A federal approval that lets a state test different Medicaid approaches, such as new benefits or delivery models.
Why it matters: Explains state-specific programs and coverage differences.
Illustrative example: A state waiver adds community support services.

Reference sourceMedicaid.gov CMS (Centers for Medicare & Medicaid Services)checked 10/9/26

CategoriesMedicare & Medicaid Terms

270/271 Eligibility Transaction

General (all payers)

Also called 270; 271; electronic eligibility inquiry

Definition: The pair of electronic transactions used to ask a payer about a member's eligibility (270) and receive the response (271).
Why it matters: Real-time checks reduce eligibility denials.
Illustrative example: A system sends a 270 and gets a 271 with copay details.

Reference sourceX12checked 10/9/26

CategoriesEDI & Clearinghouse Terms Eligibility & Benefits

276/277 Claim Status Transaction

General (all payers)

Also called 276; 277; electronic claim status

Definition: The pair of electronic transactions used to ask about a claim's status (276) and receive the response (277).
Why it matters: Automates status checks.
Illustrative example: A system checks claim status by 276.

Reference sourceX12checked 10/9/26

CategoriesEDI & Clearinghouse Terms Claims Processing

277CA Claim Acknowledgment

General (all payers)

Also called 277CA; claim acknowledgement

Definition: An electronic response that tells the submitter whether a claim was accepted or rejected at a payer or clearinghouse level.
Why it matters: Provides proof of acceptance for timely filing.
Illustrative example: A 277CA shows the payer accepted the claim on a date.

Reference sourceX12checked 10/9/26

CategoriesEDI & Clearinghouse Terms Claims Processing

278 Prior Authorization Transaction

General (all payers)

Also called 278; electronic authorization request

Definition: The standard transaction for health care service review and authorization requests and responses.
Why it matters: Used to automate authorization in some workflows.
Illustrative example: A system submits a 278 request.

Reference sourceX12checked 10/9/26

CategoriesEDI & Clearinghouse Terms Prior Authorization Terminology

42 CFR Part 2

General (all payers)

Also called Part 2; substance use disorder confidentiality

Definition: Federal regulations that protect the confidentiality of substance use disorder treatment records from certain programs, with stricter consent rules than HIPAA in many cases.
Why it matters: Affects billing and record sharing for substance use disorder programs.
Illustrative example: A program obtains patient consent that meets Part 2 requirements before disclosing records for payment.

Reference sourceSAMHSAchecked 10/9/26

CategoriesAudits & Compliance Behavioral Health Specific Terms

60-Day Overpayment Rule

Medicare and Medicaid

Also called report and return overpayments; 60 day rule; Medicare overpayment refund deadline

Definition: The 60-day overpayment rule is a federal requirement that a provider report and return a Medicare or Medicaid overpayment within a set period after it has been identified. It comes from the Social Security Act and CMS regulations.
Why it matters: Holding an overpayment past the deadline can create false claims exposure. Set up a process to review credit balances and payer refund requests, and ask counsel how the rule applies.
Illustrative example: A billing team finds a duplicate Medicare payment, reports it to the MAC, and returns the money within the required time.

Reference sourceCMS (Centers for Medicare & Medicaid Services)HHS Office of Inspector General (OIG)checked 10/9/26

CategoriesAudits & Compliance Payment & Reimbursement

834 Enrollment Transaction

General (all payers)

Also called 834; benefit enrollment file

Definition: The standard transaction plans use to send enrollment and maintenance information.
Why it matters: Explains how plans get member data from employers.
Illustrative example: A payer receives an 834 from an employer.

Reference sourceX12checked 10/9/26

CategoriesEDI & Clearinghouse Terms Eligibility & Benefits

835 Electronic Remittance Advice

General (all payers)

Also called 835; ERA file

Definition: The electronic transaction that carries payment and adjustment details from a payer to a provider.
Why it matters: Enables auto-posting of payments.
Illustrative example: A practice imports an 835 to post payments.

Reference sourceX12checked 10/9/26

CategoriesEDI & Clearinghouse Terms Payment & Reimbursement

837I

General (all payers)

Also called 837 institutional; electronic institutional claim

Definition: The electronic transaction for institutional claims, equivalent to the UB-04.
Why it matters: Facility-based programs use it.
Illustrative example: A residential program sends 837I claims.

Related termsUB-04 (CMS-1450)837P

Reference sourceX12checked 10/9/26

CategoriesEDI & Clearinghouse Terms Claims Processing

837P

General (all payers)

Also called 837 professional; electronic professional claim

Definition: The electronic transaction for professional claims, equivalent to the CMS-1500.
Why it matters: Most therapy and psychiatry claims are sent as 837P.
Illustrative example: A clearinghouse transmits an 837P batch to a payer.

Related termsCMS-1500 837I Clearinghouse

Reference sourceX12checked 10/9/26

CategoriesEDI & Clearinghouse Terms Claims Processing

988 Suicide and Crisis Lifeline

General (all payers)

Also called 988; national suicide prevention lifeline; crisis line

Definition: The 988 Suicide and Crisis Lifeline is the national three-digit number for people in suicidal crisis or emotional distress. SAMHSA, part of HHS, oversees it. People can call, text, or chat.
Why it matters: Crisis services often connect to billing through mobile crisis and crisis codes. Practices should know the number for their crisis plan.
Illustrative example: A therapist gives a client the 988 number as part of a safety plan.

Reference sourceSAMHSA HHS (U.S. Department of Health and Human Services)checked 10/9/26

CategoriesBehavioral Health Specific Terms

999 Implementation Acknowledgment

General (all payers)

Also called 999; functional acknowledgment

Definition: An electronic acknowledgment that a file was received and passed or failed syntax checks.
Why it matters: Shows the file was technically received.
Illustrative example: A 999 shows a batch was accepted.

Reference sourceX12checked 10/9/26

CategoriesEDI & Clearinghouse Terms

Quick answer: EDI Codes

What is the difference between a 277CA and a 999?

A 999 says a file was technically received and passed or failed syntax checks. A 277CA says whether each claim was accepted or rejected at the payer or clearinghouse level, and it can serve as proof of acceptance for timely filing.

Frequently asked questions: EDI Codes

What is an 837P?

The 837P is the electronic transaction for professional claims, the digital equivalent of the CMS-1500. Most therapy and psychiatry claims travel as 837P files from your system or clearinghouse to the payer.

What is an 835 electronic remittance advice?

An 835 carries payment and adjustment details from the payer to your practice. Importing it lets your system post payments automatically.

What do 270 and 271 mean in billing?

A 270 is the electronic request that asks a payer about a member's eligibility. The 271 is the payer's response, which can include copay and deductible details.

Related resources

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MCM South serves psychotherapists and psychiatrists in ten states: Georgia, Massachusetts, Connecticut, Texas, Florida, New York, Colorado, Tennessee, North Carolina and Illinois.

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