Why your dental insurance payment was less than you expected

You expected the insurer to pay more. Before anyone writes off the difference or bills the patient, read the line. Every dollar of your fee lands in one of four places: the insurer paid it, you write it off, the patient owes it, or it was denied. Some of what looks like a write-off is money the insurer still owes you.

The insurer's payment comes either as a paper or PDF explanation of benefits (EOB), or as an electronic payment file (called an ERA, or 835) with the same lines. This guide calls both the insurer's payment.

The six numbers on one line

On the line	What it means
Billed	Your office fee for the procedure, as sent on the claim.
Allowed	What the insurer says the procedure is worth under your contract or the patient's plan. Everything above it is adjusted off.
Paid	What the insurer actually paid on the line.
Write-off (contractual)	The part of your fee above the allowed amount that your contract says you write off. Under a PPO you can't bill the patient for it.
Patient owes	The patient's share of the allowed amount: deductible, coinsurance or co-payment.
Denied	A line the insurer paid nothing on, with a code that says why. Many denials can be fixed and sent again.

Two checks should always work: billed − write-off = allowed, and allowed − patient owes = paid. If a line doesn't add up, an adjustment is somewhere else on the claim; find it before you post.

The two letters in front of each code decide who pays

CO: “Contractual obligation: the office cannot bill the patient for this amount.”
PR: “Patient responsibility: the patient may owe this amount.”

So CO-45 and PR-2 are different kinds of money. The number after the letters is the reason. Here is what the reasons you see most often mean, in the words of Owedex's code list:

Code	What it means	What to do	Who usually owes it
PR-1	“Deductible amount.”	Patient's deductible. Confirm the deductible was not already met this plan year.	The patient, usually (verify with the insurer)
PR-2	“Coinsurance amount.”	Patient's percentage share. Check the percentage matches the plan's benefit level for this procedure class.	The patient, usually (verify with the insurer)
PR-3	“Co-payment amount.”	Patient's fixed co-pay.	The patient, usually (verify with the insurer)
CO-45	“Charge exceeds the fee schedule or contracted amount.”	Normal PPO write-off. Owedex checks the allowed amount against the office's contracted fee.	Nobody, if the allowed amount matches your contract. The insurer, for any part below it (verify with the insurer)
CO-16	“Claim lacks information or has a submission/billing error.”	Read the remark code (RARC) for what is missing, correct it and resubmit.	The insurer, once the claim is corrected and sent again (verify with the insurer)
CO-252	“An attachment or other documentation is required.”	Attach x-ray, narrative or perio chart and resubmit (or send through the attachment portal).	The insurer, once the attachment is sent (verify with the insurer)
CO-22	“May be covered by another payer (coordination of benefits).”	Confirm which plan is primary; bill the primary first, then send the secondary with the primary's EOB.	The other plan first (verify with the insurer)
CO-97	“Included in the payment for another service (bundled).”	Appeal only if the service was separate and distinct, with documentation.	Depends: a write-off unless the services were separate (verify with the insurer)

A worked example: a crown paid below the contract

Made-up numbers. You bill a crown at $1,200.00. Your PPO contract lists $820.00 for that code. The insurer's payment says:

Billed	Allowed	Paid	CO-45	PR-2
$1,200.00	$760.00	$380.00	$440.00	$380.00

It adds up: $1,200.00 − $440.00 = $760.00 allowed, and $760.00 − $380.00 coinsurance = $380.00 paid. The habit is to write off the whole $440.00. But the allowed amount is $60.00 below your contract, so only $380.00 of it is a true write-off. The other $60.00 is an underpayment: ask the insurer to reprocess at the contracted fee, with the fee schedule page. If it does, both its payment and the patient's share can change.

When a “write-off” is money you can still get

Paid below your contract. The allowed amount is lower than the fee your PPO contract lists for the code. The gap is owed by the insurer, not written off.
Paid below what that insurer usually pays you. No fee schedule on file? Compare with what the same insurer allowed you for the same code on its other recent payments.
A denial you can fix. CO-16 (“Claim lacks information or has a submission/billing error.”) and CO-252 (“An attachment or other documentation is required.”) are paid once the claim is corrected or the attachment is sent.
The wrong insurer. CO-22 (“May be covered by another payer (coordination of benefits).”): bill the primary plan first, then send the secondary with the primary's statement.
A bundled procedure that wasn't. CO-97 (“Included in the payment for another service (bundled).”): appeal only if the service was separate and distinct, with documentation.

What to check on every payment

The paid code is the code you billed. If not, see downcoding.
The allowed amount equals your contracted fee for that code. Keep each PPO fee schedule where the person posting can see it.
Every CO amount is a true contractual write-off, not a denial or an underpayment hiding in the write-off column.
Every PR amount matches the patient's plan: deductible not already met, the right coinsurance percentage for the procedure class.
Every denied line has a next step and a deadline. See how to appeal.
The payment reached your bank in full. See virtual card fees.

How Owedex shows it: “Don't write off”

Owedex's Post payments sheet shows each insurer payment the way you key it into your practice software: insurance paid, write-off, patient owes, and a separate Don't write off column. Denials you can fix or appeal, and the part of a write-off that makes a line paid below your contract (or below what that insurer usually pays you), go in that column, with the reason and where the claim is being worked. Amounts Owedex can't be sure about are marked “Check first” instead of being guessed.

Owedex Post payments on a made-up office: CO-16 amounts marked Don't write this off, fix and resend, then each claim's billed, allowed, insurance paid, write-off, don't write off and patient owes

Questions

Why did the insurance pay less than the allowed amount?

Because part of the allowed amount is the patient's share: a deductible, coinsurance or a co-payment. Those show with the letters PR on the insurer's statement. Allowed minus the patient's share should equal what the insurer paid.

Should I write off the difference between my fee and what insurance allowed?

Only the part your contract says to write off. If the allowed amount is below the fee your PPO contract lists for that code, the gap is an underpayment the insurer still owes you: ask for reprocessing instead of writing it off.

What does CO-45 mean on a dental payment?

In Owedex's plain-English code list: "Charge exceeds the fee schedule or contracted amount." It is normally the contractual write-off, but check the allowed amount against your contracted fee first.

See which of your write-offs are really money owed. The free check reads your insurer payments and PPO fees in your browser, compares every line with your contract and flags underpayments and fixable denials. Nothing is uploaded.

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Code meanings are Owedex's plain-English wording from its code list; the official list is kept by X12 (x12.org). What each insurer does with a code can differ: verify with the insurer. General information for dental billing staff, not legal advice. Plan terms, contracts and insurer rules vary: check the patient's plan, your contract and the insurer's provider manual.