Claims · Updated 2026-09-08 · 5 min read
What should I send when the EOB says 'send documentation'?
A documentation request is usually a held decision rather than a refusal. Send exactly what the remark code names and send the whole of it the first time.
When an Explanation of Benefits asks for documentation, read whether the payer refused the claim or paused it. Reason code 163 means the attachment is incomplete and the decision is being held — the payer has not said no, it has said not yet. Codes 250, 251 and 252 mean the required attachment is missing or invalid. In every case the instruction that matters is in the remark code beside the reason, because the remark names the specific artifact: pre-operative images, a full-arch series, current periodontal charting, an operative note, a pathology report, an itemized statement, a plan of treatment. As of September 2026 missing medical documentation was 1,815 denied dental claim lines across 33 practices and 58 payers, 2.8% of all denials, and the expensive version of that number is the second round — a resubmission that answers half the request is denied again while the filing clock keeps running.
What we measured
Denied dental claim lines by documentation-related reason, measured September 2026 across 37 dental practices and more than 170 payers.
| reason | denied lines | practices | payers | share of all denials |
|---|---|---|---|---|
| Missing medical documentation | 1,815 | 33 | 58 | 2.8% |
| Medical necessity | 1,049 | 34 | 46 | 1.6% |
| Claim submission error | 634 | 24 | 19 | 1.0% |
| Missing plan documentation | 307 | 16 | 26 | 0.5% |
Documentation requests spread across almost every practice in the measurement — 33 of 37 — and 58 different payers. This is not one carrier's habit.
What the carriers' own documents say
Delta Dental of California's published mapping carries a whole family of codes whose text says the decision is on hold rather than refused. From Delta Dental – Policy ID Mapping for CARC/RARC Health Care Policy Codes:
"Benefits decision delayed: The plan cannot make a benefit decision without all reasonably necessary information." (policy codes 5X2 to 5X5, covering the prognosis and treatment plan, a narrative, and an itemized statement)
And the code for the round that never came back:
"Benefits decision delayed: Additional documentation was not received after a previous request for information." (policy code 5X6)
The same document shows how specific a request can be, and why sending the wrong image is the same as sending nothing:
"Post & Core and related restorative/fixed prosthetics are payable only on an endodontically treated tooth. Benefits could not be determined because the submitted radiograph(s) does not depict completed root canal therapy. If root canal treatment has been completed, submit a post operative periapical image and narrative."
For sedation, Delta names the whole list rather than a category:
"Benefits for more units of general anesthesia or IV sedation than the patient's plan permits will require written documentation explaining the rationale for the extended anesthesia time. Necessary documentation, for completed treatment, includes all associated X-rays, progress notes and the complete anesthesia record and, for pre-treatment estimates, x-rays, and a narrative."
Delta's PPO and Premier scaling and root planing coverage criteria and claim policy, published under Delta Dental Covers Me, states the periodontal case in one line:
"Benefits could not be determined because of missing periodontal charting." (policy code 574)
And a data request, which is a different thing entirely and is not an appeal:
"Benefits could not be determined because of missing/conflicting information. Please submit a new claim or pre-treatment estimate with the appropriate procedure code, arch, quadrant, tooth number, and/or surface code information." (policy code 161)
One procedural instruction, from the same mapping, that offices routinely break:
"To prevent delays in processing, please do not attach a copy of this EOB to the new claim."
Why it depends on the contract
What the payer may ask for, and what it does when the answer is thin, are set by the plan and the network agreement rather than by the code.
The request list differs by procedure and by carrier. Delta's own remarks split the x-ray family four ways — missing radiographs, incomplete or invalid radiographs, missing pre-operative images, missing current films — and reading which one it is decides whether post-operative films will answer the request or be rejected as the wrong evidence.
Some documentation requests are a door left open on a limitation. Remark code N435 means the frequency approved was exceeded without supporting documentation, which is a payer saying it will reconsider with evidence. Remark code M86 says a payment was already made in the window, which is a count and takes no documentation at all.
The consequence of not answering varies. Delta's 5X6 records the request as unanswered and denies. Liberty Dental Plan's national provider guide states that a dispute missing required information, if not amended, is upheld and closed. Either way the office loses the money by silence rather than by argument.
What to do
- Read the remark code before you assemble anything. It names the artifact. Sending a periapical when the request said full-arch series buys another denial.
- Send everything named in one submission. Pre-operative and post-operative images if both are named, the charting, the narrative and the itemized statement together.
- Send current films. Several carriers distinguish current from any, and an old image satisfies neither.
- Answer with the narrative the criterion asks about, not a general one. When the code says the radiograph does not show completed root canal therapy, the narrative has to say when it was completed and the image has to show it.
- Check whether the request is a claim data error rather than a clinical one. A missing tooth number, surface, quadrant or service date is corrected on the claim and resubmitted, and there is nothing to appeal.
- Do not attach the EOB to a resubmitted claim where the carrier says not to. Attach it where an appeal packet requires it.
- Diary the date the request arrived and the filing deadline for that carrier and product. A held decision does not pause the filing clock.
Numbers last refreshed September 2026.