Almost every dental carrier refuses payment for the same five things: the procedure is not a benefit of the plan, it has been done too recently, the patient is the wrong age for it, the annual maximum is spent, or a limitations clause in the plan excludes it. What differs is which of the five leads, and how often the plan pays nothing at all. As of September 2026, across 423,733 remittance lines from 39 dental practices and 146 offices, the share of processed lines that paid nothing ranged from 5.6% at Delta Dental of Massachusetts to 31.4% at Humana — and the leading reason differed by carrier: "not a covered benefit" at MetLife, Cigna, Aetna, Anthem and UnitedHealthcare, a frequency limit at Delta Dental of Pennsylvania and Ameritas, an age limit at four Delta state companies, and the annual maximum at Delta Dental of Ohio. None of that is a clinical judgement. All of it is plan design.
One thing to fix before the table. The reason wording below is our own categorisation of what the payer's remark says, grouped into a fixed set of categories so carriers can be compared. It is not a code any carrier transmits: "frequency limitation" is our label for what the remark says, not a name any carrier uses, and we hold no carrier's legend to check it against. Carriers print their own private markers — MetLife a bare J or 16, Cigna NT or N4 — and those decode only against that carrier's own legend.
What we measured
Lines the payer had finished processing where the plan paid nothing and no part of the charge went to the patient's deductible. A deductible application is the payer charging the deductible, not refusing the procedure, so those are excluded, as are lines the payer had not finished processing. A line is one procedure on one claim.
| carrier | lines paid nothing | share of processed lines | practices | leading reason in the remark | its share | a reason on the line |
|---|---|---|---|---|---|---|
| Delta Dental (all state companies pooled) | 18,103 | 12.8% | 31 | frequency limit | 18.9% | 89.4% |
| MetLife | 7,704 | 15.5% | 29 | not a covered benefit | 23.5% | 97.4% |
| Cigna | 6,076 | 16.2% | 26 | not a covered benefit | 21.1% | 98.1% |
| Guardian | 3,102 | 11.3% | 27 | frequency limit | 14.8% | 71.9% |
| Delta Dental of Pennsylvania | 2,525 | 13.0% | 20 | frequency limit | 37.3% | 95.7% |
| Delta Dental Insurance Company — Georgia | 2,262 | 17.2% | 20 | age limit | 20.4% | 96.3% |
| Delta Dental of California | 1,661 | 9.4% | 23 | age limit | 23.2% | 91.3% |
| Delta Dental of Colorado | 1,093 | 14.6% | 14 | age limit | 23.7% | 74.0% |
| Delta Dental of Massachusetts | 1,034 | 5.6% | 19 | frequency limit | 21.0% | 96.0% |
| United Concordia | 934 | 11.3% | 18 | not a covered benefit | 13.7% | 34.5% |
| UnitedHealthcare | 784 | 27.3% | 19 | not a covered benefit | 42.6% | 93.9% |
| Humana | 638 | 31.4% | 14 | not a covered benefit | 20.5% | 42.8% |
| Delta Dental of New York | 631 | 10.2% | 13 | age limit | 24.9% | 94.5% |
| Principal Financial Group | 619 | 17.3% | 18 | frequency limit | 8.6% | 27.6% |
| Delta Dental of Washington | 608 | 11.4% | 21 | not a covered benefit | 38.7% | 88.0% |
| Delta Dental of Kansas | 521 | 11.3% | 14 | not published — too few practices | — | 63.7% |
| Ameritas | 476 | 23.2% | 18 | frequency limit | 29.6% | 87.6% |
| Delta Dental of Ohio | 475 | 16.7% | 16 | annual maximum met | 29.9% | 93.7% |
| Aetna | 472 | 26.2% | 14 | not a covered benefit | 44.9% | 93.2% |
| Anthem | 459 | 23.6% | 13 | not a covered benefit | 61.7% | 96.1% |
Ninety days of remittance lines to 9 September 2026, pooled across the practices Kaylie serves — dated by when the remittance arrived, which for most claims is weeks to months after the visit, so this is what landed in a 90-day period rather than what carriers decided in it. Every cell shown is backed by at least five separate practices; a cell backed by fewer is left out rather than shown as a small number, which is why the shares within one carrier do not add up to the last column. Delta Dental appears both as its individual state companies and as one pooled row — the pooled row is the same lines counted once at group level, not the sum of the rows above it. Two Delta companies in the Northeast and one government dental programme rest on five or six practices each and are not published here at all.
Three readings.
Concentration, not variety. At Anthem, 61.7% of everything paid at nothing arrives under a single reason; at Aetna 44.9%, at UnitedHealthcare 42.6%, and at Delta Dental of Pennsylvania 37.3% under frequency alone. A carrier's denial mix is usually one dominant story plus a long tail, which is why "why do claims get denied here" has a short answer per carrier.
Whether you are told at all is the wider spread. A reason sits on the line for 98.1% of Cigna's zero-payment lines and 27.6% of Principal Financial Group's. Read a low share as "no reason on the line", never as "the carrier stated none" — part of the gap is the payer printing nothing and part is what came through on the record, and we cannot split the two.
A zero is not always a refusal. At Delta Dental of Massachusetts, 17.0% of the lines that paid nothing were paid by another insurance plan and 13.3% were out-of-network processing — neither is the plan saying no. Bundling is the same trap in reverse: it appears in the published ranking on nine of the twenty rows above, and the work it needs is a rebilling decision, not an appeal.
What the carriers' own documents say
Cigna states in its own governing clinical document that the plan, not the carrier, settles these questions:
"These differences may include age limitations, frequency limitations, exclusion of coverage for certain procedures, and/or alternate benefit provisions. The member specific benefit plan documents [e.g., Evidence of Coverage (EOC), and/or Summary Plan Description (SPD)] supersede Cigna Dental's Clinical Coverage Determination Guidelines."
— Cigna Dental Clinical Coverage Determination Guidelines, DPPO and Indemnity, 2026
That sentence names the four leading categories in the table above and hands all of them to the employer group's plan document. Delta Dental of California, the one Delta member company that publishes its internal code library, states them the same way, one sentence per code — "The patient's annual maximum has been reached" (policy code 7G1), and for frequency, "This service has exceeded the program's frequency limitation within any twelve-month period" (Delta Dental — Policy ID Mapping for CARC/RARC Health Care Policy Codes).
Why the rate is not a league table
A carrier's share in the second column is not a measure of how hard that carrier is to bill. It moves with what the practices in front of it submit: a carrier seen mostly for large restorative work will refuse a higher share of lines than one seen mostly for cleanings, whatever its rules. The three carriers at the top of the rate column also rest on some of the smallest line counts here, between 1,802 and 2,877 processed lines each, so treat those rates as narrower evidence than Delta's or MetLife's.
Two more limits worth stating. These are lines, not dollars — a refused $1,400 crown counts once and so does a refused $35 fluoride, and nothing here supports a dollar figure. And 39 practices is the whole population measured, not a sample of American dentistry: it is skewed to the states and payers those practices bill, so read the ranking as real and the national generalisation as unmeasured.
What to do
- Work the leading reason for the carrier in front of you, not the industry average. At Anthem and Aetna that means checking coverage of the code against the group's plan document before treatment; at Delta Dental of Pennsylvania and Ameritas it means checking the interval.
- Verify per employer group. Every category in the table is set in the group's plan document, and two groups at one carrier answer differently.
- Separate the three no-payment lines that are not refusals — bundled, paid by another plan, out-of-network processing — before counting your denials, or your own denial rate will be wrong in the same way.
- Where the line carries no reason at all, call and write down what you are told against the code. Carriers differ enormously in whether they tell you, and the record you build is the only legend you will have.
Numbers last refreshed September 2026.