Billing · Updated 2026-09-08 · 6 min read

In-network vs out-of-network dental: who pays the difference?

In network the office writes the difference off; out of network the patient owes it — and carriers spell out both rules in their own member documents.

In network, the office pays the difference: a contracted dentist accepts the plan's allowed amount as payment in full and the remainder of the fee is a write-off. Out of network, the patient pays it: the plan pays its percentage of its own allowance and the dentist may bill the patient the rest of the fee, on top of the coinsurance. That second gap is balance billing, and it is separate from the deductible and the coinsurance. Out of network the measurement complicates the picture: across the twelve months to August 2026, 64.2% of out-of-network claim lines came back allowed at or above the fee the office billed, so on most of those claims there was no gap at all — and no way to learn the plan's real allowance from the remittance.

What we measured

Paid dental claim lines across the practices we serve over a trailing twelve months, aggregated so no practice, patient or employer group is identifiable. Where the allowed amount equalled the billed fee, it was exact about 99% of the time.

What the carriers' own documents say

Cigna defines balance billing with its own arithmetic:

"Balance billing: When an out-of-network provider bills you for the difference between the charges for a service and what Cigna Healthcare will pay for that service after coinsurance and the contracted fee have been applied. For example, an out-of-network provider may charge $100 to fill a cavity. If the contracted fee is $50… and the coinsurance is 50%… Cigna Healthcare will pay $25 and you will pay $25."

— Cigna Healthcare Dental Individual & Family Plan 3000/100 Schedule of Benefits, Total Network, 2025. The same entry finishes the example: because the visit is out of network, the provider may bill the remaining $50, so the patient's total is $75 — and "Balance billing charges are separate from any applicable deductible and coinsurance."

Delta states the in-network side as an obligation on the dentist:

"For covered services, participating providers agree to accept the plan's allowed amount as payment in full, with the patient responsible only for their defined cost share. For DeltaCare® USA, participating providers agree to accept the member's copayment as payment in full."

— Delta Dental, "Protect your patients beyond the chair: Avoid balance billing issues", FYI, April 23 2026.

And the out-of-network side, from Delta's own comparison of the two:

"Out-of-network providers have no contracted rates with Delta Dental; members will pay for the full cost of dental services upfront and be reimbursed only up to their plan's limits. They're responsible for any balance between the plan's limits and the provider's regular fees."

— Delta Dental Insider Update, January 23 2026. The same comparison lists three differences that are not about money at all. On unbundling: in-network dentists "agree not to charge separately for services that are part of a treatment (like a local anesthetic)", while out-of-network dentists "may charge for these services separately, making overall costs higher." On prepayment: in network, "members pay only their portion of the bill", while out of network "the dentist may charge up front for the full cost." On claims: out of network, "members will likely have to file their own claims."

MetLife states the in-network ceiling in its strongest form — it holds even when the plan pays nothing:

"When the plan allowance is not reimbursed in full or in part by the benefit plan, any difference is the responsibility of the participant up to the plan allowance. The participant is not responsible for any amount that exceeds the plan allowance."

— MetLife Preferred Dentist Program (PDP) Resource Manual, 2025.

One warning about the phrase itself. It carries two meanings and they are not neighbours. Out of network it names the patient's legitimate balance, which is the subject of this article. Inside a participating-dentist agreement it names a breach — a contracted dentist billing the patient for an amount the contract had already made the office's write-off — which is why Delta's advice on the subject is addressed to its own dentists rather than to members. Establish which of the two a document means before acting on it.

Why it depends on the plan

"In network" is not one status. A dentist contracted with Delta Dental Premier but not PPO is contracted — the patient is protected up to the Premier maximum plan allowance — but on a Delta Dental PPO MAC plan that same dentist is paid the PPO fee and may bill the patient the difference up to the Premier allowance. Treating a Premier dentist as out of network bills a patient who is protected, and reports a write-off of zero on a contract that forgave hundreds.

Out of network, what the plan pays from is also an employer choice. It may be a percentile of area charges, a third-party benchmark such as FAIR Health, or the plan's own in-network fee schedule. On a plan of the last kind the patient owes the coinsurance gap and the balance-billing gap, both measured against the smallest allowance in the structure.

Going out of network also resets nothing. Cigna's commercial dental summaries state that "All deductibles, plan maximums, and service specific maximums cross accumulate between in and out of network", and that frequency limitations do the same.

What to do

• Establish the patient's network status and your own contract status separately. They are two facts and the second is a property of your office, not of their plan.
• Out of network, quote two numbers: the coinsurance share of the plan's allowance, and the balance between that allowance and your fee. A single "the plan covers 80%" figure is what produces the surprise.
• In network, write off the difference and bill the patient only the defined cost share. Billing above the allowance on a covered service is a contract breach at every carrier quoted here.
• Do not derive an out-of-network allowance from remittances where the allowed amount equals your fee — that is two out-of-network lines in three.
• Tell an out-of-network patient in advance that they may have to pay in full and file their own claim. Delta says both plainly, and neither surprises well after treatment.

Numbers last refreshed August 2026.

All articles · Kaylie