What is an ERA (835 remittance) in medical billing? How to read it and post it
An ERA, or electronic remittance advice, is the electronic explanation of how a payer processed each claim, sent in the standard 835 format. Numetix matches ERAs to bank deposits so payments and adjustments agree with the ledger. This guide explains what an ERA contains, how to read it, and how to post it.
QUICK ANSWER: WHAT IS AN ERA IN MEDICAL BILLING?
An ERA is the electronic remittance advice, sent in the HIPAA-standard X12 835 format, that explains how a payer handled each claim.
It lists what was billed, what was paid, and every adjustment, with a group code and a reason code that explain each difference.
Match each ERA to the deposit it explains, post payments and adjustments to the right accounts, and work denials before they age.
Numetix is the expert-led, AI-powered, human-in-the-loop bookkeeping layer for medical and dental practices, so remittances, deposits, and receivables are reconciled by software and reviewed by a named person. The sections below explain the format, the codes, and a posting routine.
What is an ERA, and what does 835 mean?
A remittance advice tells a provider how a payer decided each claim and how the payment was calculated. The electronic version is the ERA. The CMS Medicare Claims Processing Manual says ERA transactions must be produced in the current HIPAA-compliant ASC X12 835 version 5010 (CMS Medicare Claims Processing Manual, chapter 22), so 835 is the standard layout that billing software reads.
What does an ERA contain?
Element | What it shows | Why it matters for your books |
|---|---|---|
Claim and patient identifiers | Which claim the line belongs to | Lets you post to the right patient account |
Billed and allowed amounts | What you charged and what the payer allows | The gap is usually a contractual adjustment |
Payment amount | What the payer is paying | Must match the deposit |
Adjustments with group code and reason code | Each reduction and why | Drives write-offs, patient balances, and appeals |
Remark codes | Extra explanation on some lines | Often tells you what to fix |
Patient responsibility | Amounts the patient may owe | Becomes a patient receivable |
Our guides to CARC denial codes and RARC remark codes explain the code families.
How do group codes and reason codes read on an ERA?
Each adjustment pairs a group code with a reason code. CMS describes CO as contractual obligations, generally a write-off for the provider that is not billed to the patient, PR as patient responsibility, typically deductible and copay amounts, and OA as other adjustments when no other group code applies (CMS Medicare Claims Processing Manual, chapter 22). The reason codes come from the X12 claim adjustment reason code list (X12 claim adjustment reason codes).
Group code | Meaning | Typical handling |
|---|---|---|
CO | Contractual obligation | Adjust off the account per the contract |
PR | Patient responsibility | Bill the patient or the secondary payer |
OA | Other adjustments | Review the reason code before you act |
The contractual adjustment and write-off glossary entries explain how those adjustments hit the books.
How do you post an ERA and reconcile it to the bank?
Total the payments on the ERA and find the matching deposit in the bank.
Post each payment and adjustment to the correct patient account.
Record contractual adjustments separately from write-offs and bad debt.
Move patient responsibility amounts to patient balances.
Flag denied or short-paid lines for follow-up, and note the reason code.
If claims pass through a clearinghouse, see our guide to what a clearinghouse in medical billing does.
What problems show up most?
A deposit that covers several ERAs, or one ERA split across several deposits.
Payments posted to the wrong patient account because of a matching error.
Adjustments lumped together, which hides denials inside write-offs.
Patient balances that never get billed because the PR amount was not moved.
Frequently asked questions
Is an ERA the same as an EOB?
No. An explanation of benefits goes to the patient and describes what the plan covered and what the patient may owe. An ERA goes to the provider and explains how each claim was paid and adjusted, in a format billing software can read and post.
Do I need a clearinghouse to receive ERAs?
Many practices receive ERAs through a clearinghouse or a payer portal, and some payers send them directly. The right route depends on your billing software and payers. Ask your billing vendor which payers send ERAs automatically and which still require manual downloads or paper remittances.
How often should I post ERAs?
Post ERAs as they arrive and reconcile deposits at least weekly, so unmatched payments and denials surface early. Then confirm at month end that posted payments, adjustments, and patient balances agree with the ledger before you close the books for the month.
Numetix is the expert-led, AI-powered, human-in-the-loop bookkeeping layer that matches remittances to deposits and receivables with a named reviewer. See our accounting services built for healthcare practices.
Numetix is an AI-first accounting firm. AI runs the bookkeeping, tax, payroll, and reporting workflow. Industry experts handle the judgment, month-end close, review, and advisory. We serve founder-led service firms across law, consulting, IT, healthcare, creative, and nonprofit. Headquartered in California, serving clients nationwide.
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