"Delta Dental" is not one insurer. It is a group of member companies, each underwriting its own contracts and adjudicating its own claims, and their refusals do not look alike. As of September 2026, across 18,103 Delta lines where the plan paid nothing, the share of processed lines that paid nothing ranged from 5.6% at Delta Dental of Massachusetts to 17.2% at Delta Dental Insurance Company's Georgia book — a threefold spread — and the leading reason moved with the state company: an age limit in California, New York, Colorado and Georgia, a frequency limit in Pennsylvania and Massachusetts, the plan not covering the procedure in Washington, and the annual maximum in Ohio. Pooled across every state company, Delta's leading reason is a frequency limit at 18.9%, which is the number to stop using: it is an average of state books that disagree.
What we measured
| Delta company | lines paid nothing | share of processed lines | practices | leading reason in the remark | its share | a reason on the line |
|---|---|---|---|---|---|---|
| Massachusetts | 1,034 | 5.6% | 19 | frequency limit | 21.0% | 96.0% |
| California | 1,661 | 9.4% | 23 | age limit | 23.2% | 91.3% |
| New York | 631 | 10.2% | 13 | age limit | 24.9% | 94.5% |
| Kansas | 521 | 11.3% | 14 | not published — too few practices | — | 63.7% |
| Washington | 608 | 11.4% | 21 | not a covered benefit | 38.7% | 88.0% |
| Pennsylvania | 2,525 | 13.0% | 20 | frequency limit | 37.3% | 95.7% |
| Colorado | 1,093 | 14.6% | 14 | age limit | 23.7% | 74.0% |
| Ohio | 475 | 16.7% | 16 | annual maximum met | 29.9% | 93.7% |
| Insurance Company — Georgia | 2,262 | 17.2% | 20 | age limit | 20.4% | 96.3% |
| all state companies pooled | 18,103 | 12.8% | 31 | frequency limit | 18.9% | 89.4% |
Ninety days of remittance lines to 9 September 2026, dated by when the remittance arrived rather than when the service happened: lines where the payer had finished processing, the plan paid nothing, and none of the charge went to the patient's deductible — a deductible application is the payer charging the deductible, not refusing the procedure. The pooled row is the same lines counted once at group level, not the sum of the rows above it. Every cell is backed by at least five separate practices and cells backed by fewer are left out, which is why Kansas has no publishable leading reason and why the shares within a row do not add to the last column. Two Delta companies in the Northeast rest on five practices each and are not published here at all. The reason wording is our own categorisation of what the remark says, grouped so companies can be compared; it is not a code Delta transmits.
Three readings, and the first is the useful one.
Age is the Delta pattern the pooled number hides. Four state companies lead with an age limit, at 20.4% to 24.9% of everything they pay nothing on, and in the pooled view age falls to third at 14.8%. An office in Georgia or New York verifying Delta the way a national summary suggests is checking the wrong field first.
Pennsylvania and Washington are the concentrated books. Washington refuses 38.7% of its nothing-paid lines as not a benefit of the plan and Pennsylvania refuses 37.3% on frequency alone — the two highest single-reason concentrations among these companies. In Pennsylvania that means the interval, not the code, is where the money goes.
A zero is not always a refusal, and Massachusetts proves it. It has the lowest rate here, and of the lines it did pay nothing on, 17.0% were paid by another insurance plan and 13.3% were out-of-network processing. Neither is the plan saying no; both are lines that need posting, not appealing. Massachusetts is also the only company in the table where out-of-network processing reaches the published ranking at all.
Two more differences worth knowing. New York states a claim submission error on 11.1% of its nothing-paid lines, the highest here, so a New York zero is more often a claim to correct and resubmit than a benefit to explain. And Ohio is the only company led by the annual maximum, at 29.9% — a spent maximum is not appealable, only rescheduleable.
What Delta's own documents say
Delta Dental of California is the one member company that publishes its internal code library, and it writes each of the categories above as a plain sentence. Frequency:
"This service has exceeded the program's frequency limitation within any twelve-month period. This service has already been provided within the frequency period, therefore a new service cannot be benefited." (policy code 776)
The annual maximum, which is a different rule from frequency even though both arrive as a zero:
"The patient's annual maximum has been reached." (policy code 7G1)
Both from Delta Dental — Policy ID Mapping for CARC/RARC Health Care Policy Codes, pinned at Delta Dental of California network scope.
That document is California's, and it says so — it is pinned to Delta Dental of California's own network scope. That is the trap the table is really about: nothing in it decodes another member company's codes, because each member company runs its own claim system and its own remark list. A Colorado code matched against California's table gives a confident wrong answer, and the sentence printed beside the code is the only thing you can safely read it with.
Why the state company is the unit, not "Delta Dental"
Each Delta member company underwrites its own contracts, sells to its own employer groups and runs its own claim system. What reaches the office as one brand is a different insurer per state, and the mix in the table is the combined effect of two things that both vary: what those employers bought, and how that company words a refusal. Colorado's 74.0% and Kansas's 63.7% in the last column are the visible version of the second — on 26.0% and 36.3% of the lines those two companies paid nothing on, there was no reason on the line at all. Read that as "no reason on the line", not as "the company gave none": part of the gap is the payer printing nothing and part is what came through, and the two cannot be separated here.
What to do
- Verify against the state company on the card, not against "Delta Dental". The leading reason differs by state and so does the code library.
- In Georgia, New York, California and Colorado, check the patient's age against the code before treating — age limits lead all four.
- In Pennsylvania, check the interval first. Frequency is 37.3% of everything paid at nothing there, and it is answerable from the patient's own history.
- Never decode a Delta code from another member company's list. Read the sentence beside it, and where there is no sentence, call that company.
- Post the not-refusals separately: coordination of benefits and out-of-network processing look identical to a denial in a report and need entirely different work.
Numbers last refreshed September 2026.