Insurance Billing
How to Read an ERA/EOB as a Dietitian (and Post Payments Without the Headache)
A plain-English guide to remittances for RDs: allowed amounts, adjustment codes (CO-45, PR-1, CO-97), spotting underpayments, posting payments, and when a 'paid' claim still shorts you.
Getting a remittance is supposed to be the good part — the money arrived! But if you've ever stared at an EOB full of codes like CO-45, PR-1, and OA-23 wondering whether you were just underpaid, you know it's where insurance billing saves its final trick.
Here's the RD-specific decoder: what each line actually means, the three checks that catch underpayment, and how posting works — manually or automatically.
EOB vs. ERA in one paragraph
They carry the same information. The EOB is the human-readable PDF; the ERA (the X12 "835" file) is the electronic version your clearinghouse or software receives. If you're reading PDFs and typing numbers into a spreadsheet, you're doing by hand what the ERA exists to automate. Enroll for ERAs (and EFT for the money itself) with every payer you're contracted with — it's free and usually a one-page form.
Anatomy of a remittance line
For each claim line (say, 97803 × 4 units), the remittance shows:
| Field | Meaning | Example |
|---|---|---|
| Billed amount | Your charge | $180.00 |
| Allowed amount | The payer's contracted price — the number that matters | $124.00 |
| Adjustments | Coded differences, each with a group + reason code | CO-45: $56.00 |
| Patient responsibility | Copay/coinsurance/deductible — you bill the patient | PR-3: $20.00 |
| Paid amount | What the payer sends you | $104.00 |
The equation to keep in your head: Billed = Paid + Patient responsibility + Write-offs. If those don't reconcile, something on the line deserves a second look.
The adjustment codes dietitians actually see
Adjustment codes have a group (who absorbs it) and a reason (why):
- CO — Contractual Obligation. You absorb it; the patient can't be billed.
- PR — Patient Responsibility. Bill the patient.
- OA — Other Adjustment. Usually informational (e.g., paid by another payer).
The frequent flyers:
| Code | What it means | What to do |
|---|---|---|
| CO-45 | Charge exceeds contracted rate | Normal write-off — but verify allowed amount matches your fee schedule |
| PR-1 / PR-2 / PR-3 | Deductible / coinsurance / copay | Bill the patient promptly |
| CO-97 | Bundled into another service | Check what it was bundled with; often appealable if wrongly applied |
| CO-16 | Claim lacks information | Effectively a denial — find the missing element, resubmit |
| CO-18 | Duplicate claim | Confirm you didn't double-submit; if not, the payer mis-matched |
| CO-29 | Timely filing expired | The unforgivable one — see our denials guide |
| CO-151 / CO-119 | Units/frequency exceed limits | Compare against the plan's visit and unit caps from your verification |
The three checks that catch underpayment
Run these on every remittance — they take two minutes with practice, or zero with software:
- Allowed vs. contract. Divide the allowed amount by units and compare with your fee schedule for that CPT. Payers do misprice claims — wrong fee schedule, outdated rate — and they don't announce it. If you never check, silent underpayment becomes a permanent revenue leak.
- Units paid vs. units billed. A 4-unit claim paid at 3 units looks "paid" in every dashboard, but you just donated 15 minutes of clinical work. Underpaid units are appealable when your documentation supports the time.
- PR amounts vs. what you told the patient. If the remittance says the patient owes $35 and you quoted $20 at booking, reconcile before the balance ages into an awkward conversation.
Posting: the chore that keeps your books honest
"Posting" means recording the remittance against the session: paid, written off, patient balance. Done consistently, it gives you the three numbers that actually describe a practice's health — collected per session, outstanding patient balances, and payer aging. Done inconsistently, it produces the classic private-practice fog: "I think insurance pays me eventually?"
Manual posting from EOBs takes 5–10 minutes per remittance. At 40–60 sessions a month, that's another 3–5 hours — and it's the task practices most often let slide, which is exactly how underpayments and unbilled patient balances hide.
How Alva helps: Alva enrolls your ERAs, posts payments to sessions automatically, runs the three underpayment checks on every remittance, and flags lines that need a human decision — so "did I actually get paid correctly?" becomes a question your software answers continuously instead of one you investigate in April. Try it free for 7 days; $99/month after.
Frequently asked questions
What's the difference between an EOB and an ERA?
Same information, different format. An EOB (Explanation of Benefits) is the human-readable document; an ERA (Electronic Remittance Advice, the 835 file) is the machine-readable version delivered to your clearinghouse or software. The ERA is what enables automatic payment posting.
What does CO-45 mean on my remittance?
CO-45 is a contractual adjustment: the difference between your billed charge and the payer's allowed amount under your contract. It's normal — you write it off and cannot bill the patient for it. If CO-45 seems too large, check the allowed amount against your fee schedule; payers do occasionally pay below contract.
Why did insurance pay less than my contracted rate?
Common causes: fewer units were approved than billed, the claim processed under the wrong fee schedule, the patient's deductible applied (PR-1, meaning the patient owes it), or a secondary edit reduced payment (like CO-97, bundling). Compare allowed amount per unit against your contract — silent underpayment is common enough that spot-checking every remittance matters.
What does it mean to 'post' a payment?
Recording the remittance against the specific session: insurance paid X, contractual write-off Y, patient owes Z. Accurate posting keeps your books truthful, triggers correct patient billing, and surfaces underpayments. With ERAs, software can do this automatically.
How long does it take to get paid after submitting a claim?
Electronically submitted clean claims typically pay in 14–30 days from most commercial payers. If a claim is over 30 days with no remittance, check its status — most states have prompt-pay laws requiring payers to process clean claims within 30–45 days.