How is ERA done? In three separable jobs rather than one. You enroll with each payer so it agrees to send you an electronic remittance advice, the X12 835 file. The payer generates that file when adjudication finishes and delivers it to your clearinghouse mailbox. Your software pulls it, posts every service line against the matching claim, and someone ties the file's trace number back to the bank deposit. Enrollment is done once per payer. The other two run every business day, and that is where the money is won or lost.
One note on the acronym, since other industries use it for other things. In dental billing, ERA means electronic remittance advice, the machine readable twin of the explanation of benefits. If those two still run together in your head, our piece on the difference between an ERA and an EOB separates them.
Who performs each part, and who to call when it stalls
The most useful thing to know about ERA is that no single party controls it. Four do, and knowing which one owns a step saves an afternoon of calling the wrong number.
| Step | Who performs it | Who to call when it breaks |
|---|---|---|
| Adjudicate the claim and generate the file | The payer | Payer provider services, with the claim number |
| Deliver the file to a mailbox | The payer's vendor or your clearinghouse | Clearinghouse support, with the payer ID |
| Move the money | The payer's bank to yours by ACH | Your bank, with the trace number |
| Retrieve the file into the ledger | Your practice management software | Software support, with a sample file |
| Post lines and work exceptions | Your team | Nobody. This one is yours |
Notice that the money and the explanation travel on separate tracks. That single fact explains most ERA confusion, including the classic deposit that arrives with nothing to post against it.
Enrollment, the part that is done once per payer
Enrollment is paperwork, and it fails on identifiers far more often than on banking details. The payer is trying to match your application to a provider record it already holds. Anything that does not match exactly comes back.
| What the payer asks for | Where you get it | The trap |
|---|---|---|
| Practice legal name and tax identification number | Your W-9 | A doing business as name instead of the legal name is a routine rejection |
| Group NPI, type 2 | NPPES record | Some payers key remittances to the individual type 1 NPI instead, so ask which |
| Payer assigned provider or office number | Your participating agreement or a past remittance | A number inherited from a prior owner routes files to somebody else |
| Receiver or trading partner identifier | Your clearinghouse | The wrong one sends your files to a previous vendor's mailbox, silently |
| Bank routing and account number, voided check or bank letter | Your bank | EFT is usually a separate approval even on the same form |
| Authorized signature | An owner or officer | An office manager signature is a common reason for return |
Timing is commonly quoted at two to six weeks per payer as of this writing, though some approve in days and others take longer. Work in descending order of claim volume, and stop when the next payer sends you fewer remittances a year than the enrollment takes to complete. Our breakdown of whether ERA is worth enrolling at all has the arithmetic for that cutoff.
Reading the file: four levels, nested
An 835 is not one flat list. It is a set of nested levels, and each level answers a different question. Reading it in this order is how posting gets done correctly.
| Level | Key segments | The number you take from it |
|---|---|---|
| File | BPR, TRN, N1 | Total paid, payment method, the trace number, the payer and payee |
| Claim | CLP, NM1, REF | Claim status, total billed, total paid, patient responsibility, the payer's claim control number |
| Service line | SVC, DTM, CAS, AMT | The CDT code, billed, allowed, paid, and an adjustment for every unpaid dollar |
| Provider | PLB | Money added or removed outside any claim, such as an overpayment recovery |
The claim status field is the fastest sorting tool in the file and the one most teams never open. It distinguishes a processed payment from a denial, from a claim forwarded to another payer, from a reversal of a prior payment. Sort on it before posting and a stack of remittances becomes three short queues. A fuller tour of the transaction itself is in our guide to the dental ERA and the X12 835.
The arithmetic has to balance, which is what makes posting automatic
This is the mechanic that lets software post without guessing. On every claim, the billed amount equals the plan payment plus every adjustment amount reported against it. Nothing is left over. At the file level, the total payment equals the sum of the claim payments, adjusted for anything in the provider level segment.
Here is an illustrative two line claim. The figures are invented for the arithmetic.
| Line | Billed | Allowed | CO write off | PR deductible | PR coinsurance | Plan paid |
|---|---|---|---|---|---|---|
| D0120 periodic oral evaluation | 65 | 45 | 20 | 0 | 0 | 45 |
| D4341 scaling and root planing, per quadrant | 380 | 250 | 130 | 50 | 40 | 160 |
| Claim total | 445 | 295 | 150 | 50 | 40 | 205 |
Read across the second row: 130 plus 50 plus 40 plus 160 equals 380, the billed amount. Read the totals row: 150 plus 90 plus 205 equals 445. If your posted ledger does not reproduce those sums, a line was lumped.
Lumping is the expensive part. The 150 in the CO column is a contractual write off you agreed to absorb. The 90 in the two PR columns is collectible from the patient or a secondary plan. Post all 240 as one adjustment, which is exactly what a hand entry shortcut does, and 90 dollars of real balance disappears with nothing in the ledger looking wrong. The claim shows closed. The account shows zero.
Posting, in the order it has to happen
- Match the claim. Use the payer's claim control number or your own patient account number from the file, not the patient name. Names collide, numbers do not.
- Post the line payment. One amount per CDT code, never a single lump per claim.
- Post the CO adjustments as contractual write offs. These close.
- Leave the PR adjustments open. Deductible, coinsurance and copay amounts become a secondary claim or a patient balance, and they need a next step attached the same day.
- Store the reason codes on the line. The CARC and RARC are why a line paid short, and they are your denial trend data later. Our reference on CARC and RARC codes covers how to read them.
- Handle provider level adjustments separately. A recovery or interest entry belongs to the file, not to any patient ledger, and posting it against a claim corrupts both.
- Reassociate. Match the trace number in the file to the trace on the ACH deposit. Expect one deposit to cover several files, so match on trace numbers rather than dollar amounts.
Federal operating rules adopted under HIPAA require the payer to carry that trace number and to deliver the remittance within a short window of the payment, commonly described as three business days. Rules change, so confirm the current requirement with CMS rather than taking a date from an article.
What the software does and what a person still has to judge
Auto posting is accurate on arithmetic and blind on judgment. Three checks stay human, permanently.
Is the allowed amount right? The file reports what the plan allowed. It does not know your contracted rate. A line paid exactly as instructed can still be underpaid, which is the subject of our guide to catching underpayments against contracted allowables.
Is this takeback legitimate? Provider level recoveries are sometimes correct and sometimes not, and they arrive with no claim attached to argue about.
Does this denial deserve an appeal? Zero dollar files carry denials, and denials carry deadlines that run from the date on the file, not the date somebody opened it.
Set the split before you turn automation on, not after. The practical boundary is laid out in our piece on automated payment posting and what still needs review, and the wider loop from adjudication to a closed account is in what the ERA cycle covers.
Curo reads the 835 line by line, posts the payment and the write off separately from patient responsibility, and flags any line where the allowed amount disagrees with the contracted rate on file, which is the check auto posting alone will never make. You can see that comparison on your own remittances through EOB reconciliation.
A closing note that costs nothing to act on. Pick one remittance from last week, open the file rather than the printed copy, and check the arithmetic on a single claim by hand. If billed equals paid plus adjustments, and the CO and PR amounts landed in different places in your ledger, your process is sound. If they did not, you have just found where the money goes, and you found it on one claim instead of a year of them.