A family medicine practice we work with sent a claim last week for a 68-year-old Medicare Advantage patient seen for a follow-up. The visit was straightforward. The claim carried four diagnosis codes pulled from the problem list: type 2 diabetes without complications (E11.9), prediabetes (R73.03), essential hypertension (I10) and hyperlipidemia (E78.5). The first two codes cannot legally sit on the same claim. Prediabetes is a code for abnormal glucose in someone who does not have diabetes, and the ICD-10-CM tabular list says so with an Excludes1 note. Until this month, UnitedHealthcare's Medicare Advantage plans would have paid that claim without comment. Now they say they will not.
In its February 2026 Medicare Advantage reimbursement policy update bulletin, UnitedHealthcare stated that it "will begin enforcing the application of Excludes 1 guidelines across all claim types effective March 1, 2026, to include outpatient and professional claim types," and pointed providers to its updated Diagnosis Code Reimbursement Policy. The bulletin notes that when the policy was first announced, the Excludes1 requirement applied only to inpatient claims. Claims that do not comply "may be subject to edits or denials."
This is not a new coding rule. Excludes1 has been part of ICD-10-CM since the code set took effect on October 1, 2015. What is new is that a large Medicare Advantage payer is now going to check professional claims against it. Other payers have run ICD-10 Excludes1 edits on commercial claims for years, and in our experience the practices that get hit are the ones whose EHR sends the whole problem list to the claim. This article explains the rule, the pairs we see most in office practice, and the workflow fix.
Key takeaways
- An Excludes1 note means "not coded here": the two conditions cannot be reported together because one is defined as not being the other.
- UnitedHealthcare Medicare Advantage applies Excludes1 edits to professional and outpatient claims for dates of service on or after March 1, 2026; other payers already do.
- The official guidelines allow an exception when the two conditions are genuinely unrelated, but payer edit engines do not always honor it, so expect to document and appeal.
- Most conflicts come from problem lists that were never cleaned up, not from coder error.
- Your practice management scrubber can catch these before submission if the ICD-10 edit tables are turned on and current.
What an Excludes1 note actually says
ICD-10-CM has two kinds of exclusion notes, and the difference is the whole point. An Excludes1 note is a pure exclusion. The ICD-10-CM Official Guidelines for Coding and Reporting, Section I.A.12.a, describe it as "NOT CODED HERE": the code excluded should never be used at the same time as the code above the note, because the two conditions cannot occur together. The classic example in the guidelines is a congenital form of a condition versus an acquired form. You have one or the other.
An Excludes2 note means "not included here." The excluded condition is not part of the code above the note, but a patient may have both, so both may be reported when documented. Excludes2 is permission; Excludes1 is prohibition. Payers enforcing Excludes1 edits are enforcing the prohibition.
The guidelines include one exception, added for fiscal year 2017 after coding professionals pointed out that some Excludes1 pairs describe conditions that can genuinely coexist when they are unrelated. If the two conditions are documented as unrelated, both may be reported. The guidelines also say that when it is not clear whether the conditions are related, query the provider. In practice, the exception is a documentation and appeal matter. The payer's edit engine sees two codes and stops; a human at the payer has to read your note to agree that the conditions are unrelated.
The pairs that trip office practices
These are the conflicts we see most often when we audit primary care and medical specialty claims. Each one is a real Excludes1 relationship in the current tabular list, and each one usually arrives on the claim by way of a stale problem list.
| Codes on the claim together | Why it conflicts | What the record usually shows | Fix |
|---|---|---|---|
| E11.9 type 2 diabetes and R73.03 prediabetes | R73 (elevated glucose) carries Excludes1 for diabetes mellitus E08 to E13 | Patient progressed to diabetes; prediabetes stayed on the problem list | Resolve R73.03 on the problem list; report only the diabetes code |
| N39.0 urinary tract infection, site not specified, and N30.0- acute cystitis | N39.0 has Excludes1 for UTI of a specified site such as cystitis | Physician documented cystitis; the template added UTI | Report the specified site only |
| R51.9 headache and G43.- migraine | R51 carries Excludes1 for migraine and other headache syndromes G43 to G44 | Symptom code left on after the migraine diagnosis was made | Report the migraine; drop the symptom code |
| M54.50 low back pain and M51.26 or M54.4- lumbar disc displacement or lumbago with sciatica | M54.5 has Excludes1 for lumbago due to disc displacement and lumbago with sciatica | Imaging confirmed the disc; the pain code was never retired | Report the definitive diagnosis |
| F32.- single-episode depression and F33.- recurrent depression | F32 carries Excludes1 for recurrent depressive disorder F33 | Two clinicians coded the same patient differently over time | One depression code, matching the current documentation |
| J06.9 acute upper respiratory infection and J02.0 streptococcal pharyngitis | J06 carries Excludes1 for streptococcal pharyngitis | Rapid strep positive; the presenting URI code stayed | Report the strep pharyngitis |
| I10 essential hypertension and O10 to O16 hypertension in pregnancy | I10 carries Excludes1 for hypertensive disease complicating pregnancy | Prenatal patient with pre-existing hypertension coded from the general list | Use the obstetric hypertension code |
Notice the pattern in the third column. Almost none of these are a coder choosing two codes. They are a physician resolving a diagnosis in the note while the EHR keeps sending the old one. A symptom code that was correct at the first visit becomes a conflict at the second.
What an Excludes1 edit denial looks like and what to do with it
UnitedHealthcare's bulletin says claims may be subject to "edits or denials" and refers to the Diagnosis Code Reimbursement Policy for details. From what we have seen with payers that already run these edits, the line usually arrives as a diagnosis-related denial: CO-11 (diagnosis inconsistent with the procedure) or CO-16 with a remark such as M76 (missing, incomplete or invalid diagnosis), sometimes with the payer's own remark text naming the conflict. The wording will vary by payer and by clearinghouse translation, so read the remark code rather than the group code.
The fix is a corrected claim, not an appeal, in almost every case. Remove the code that no longer describes the patient, resubmit with frequency code 7 and the original claim number, and correct the problem list so it does not happen next visit. Appeal only when the two conditions are genuinely unrelated and the note says so. Then quote the Official Guidelines exception, attach the note, and expect a manual review. In our experience payers do honor the exception when the documentation is explicit; they do not honor it when the note is silent.
One more operational point. Excludes1 edits are applied to the claim, not to the diagnosis pointer. It does not matter that the conflicting code was pointed at a different line or was listed fourth. If it is on the claim, it is in the edit.
Fixing the source: the problem list and the scrubber
Two controls stop most of this. The first is in the EHR. Most systems let you choose whether the encounter diagnoses come from what the clinician marked as addressed today or from the full active problem list. Send only the addressed diagnoses. Then schedule problem list cleanup: when a symptom code is replaced by a definitive diagnosis, the symptom is resolved, not left active. This is a five-minute habit at the end of a visit and it is the single most effective fix we know.
The second control is in the practice management system or clearinghouse. Almost every claim scrubber includes an ICD-10 edit set with Excludes1 pairs, but it is often turned off or running on an old table because it "created too many alerts" during the ICD-10 transition. Ask your vendor to turn it on, confirm the table is the fiscal year 2026 version (effective October 1, 2025), and run it on Medicare Advantage claims first. Expect a spike in scrubber holds for two or three weeks while problem lists are cleaned, then a steep drop. A held claim fixed in ten minutes is cheaper than a denial worked in forty.
Coders and billers who want to work through Excludes1 and Excludes2 with real charts can do so in the Revelrex training EHR, and our medical coding team runs diagnosis-conflict audits on request.
Questions we hear
Does this apply to UnitedHealthcare commercial plans too?
The March 1, 2026 statement is in the Medicare Advantage bulletin and refers to the Medicare Advantage Diagnosis Code Reimbursement Policy. UnitedHealthcare has published diagnosis code policies for its other lines of business separately; check the commercial and Community Plan policy pages for their own effective dates rather than assuming. Regardless of the payer, the coding rule is the same, so we would apply the fix to every claim.
Will this affect risk adjustment for our Medicare Advantage patients?
Indirectly. A claim that is denied for an Excludes1 conflict does not reach the plan's encounter data until it is corrected, so any hierarchical condition category diagnoses on that claim are delayed. More important, plans and CMS auditors read a chart with contradictory diagnoses as poor documentation. Clean problem lists help you on both counts.
Our physicians say the patient really has both conditions. What then?
Sometimes they do, and the guidelines allow it when the conditions are unrelated. The note has to say so in words: for example, that the headache being treated is a tension-type headache distinct from the patient's migraine disorder. Then report both, expect the edit, and appeal with the note. If the note does not distinguish them, query the physician before the claim goes out rather than after the denial.
What to do this week
- Pull all UnitedHealthcare Medicare Advantage claims for dates of service since March 1, 2026 and run them through your scrubber with ICD-10 Excludes1 edits enabled.
- Ask your practice management or clearinghouse vendor to confirm the Excludes1 edit table is on and at the fiscal year 2026 version.
- Change the EHR setting so claims carry only the diagnoses addressed at the visit, not the full problem list.
- Give clinicians the table above and a ten-minute problem list cleanup routine for the top conflicts.
- Set up a worklist for CO-11 and CO-16 with diagnosis remarks so these denials route to a coder, not to the general follow-up queue.
