E66.2 Maps to HCC 48 in V28. Do Not Also Code E66.01

E66.2 maps to HCC 48. It does not open a second payment HCC if E66.01 is also on the chart. E66.01 has Excludes1 for E66.2. One bucket.

Open the live E66.2, E66.01, and E66.813 cards before you invent a respiratory HCC or a second 48. This page is the desk table for that leftover. It is not a rewrite of the obesity E66.9 guide. That leftover is the unspecified dead map. This leftover is obesity hypoventilation syndrome (OHS) / Pickwickian plus the Excludes1 walk.

*Current as of September 4, 2026. V28 mapping and CNA factors come from the live code pages named below and the 2026 Final ICD-10-CM Mappings. Non-PACE Medicare Advantage uses 100% V28 for payment year 2026. PACE follows a separate transition. Look the exact codes up. Do not code from this recap.*

Quick answer

Yes. E66.2 maps to CMS-HCC V28 HCC 48, Morbid Obesity. The source-labeled community non-dual aged reference coefficient is 0.186. Official title: morbid (severe) obesity with alveolar hypoventilation. Inclusion terms: obesity hypoventilation syndrome (OHS) and Pickwickian syndrome.

E66.2, E66.01, and E66.813 sit in the same bucket. Reporting two of them still pays 48 once. G47.33 is not OHS. Look that card up. Do not invent an HCC for it.

Same bucket as E66.01. Excludes1 blocks the stack.

The live HCC 48 card lists 9 ICD-10-CM codes. E66.2, E66.01, and E66.813 are three of them. The PY2026 V28 map file rows for this desk:

`E6601,48.0,,,`

`E662,48.0,,,`

`E66813,48.0,,,`

The live E66.01 card lists Excludes1: morbid (severe) obesity with alveolar hypoventilation (E66.2). Do not assign both. When the note supports OHS / Pickwickian, use E66.2. Leave E66.01 off.

E66.813 names class 3 obesity without the respiratory syndrome. It maps to the same 48. It does not replace E66.2 when alveolar hypoventilation is documented, and it does not open a second 48.

Do not treat OSA as OHS

G47.33 is obstructive sleep apnea (adult) (pediatric). The live card shows V28 not mapped and V24 not mapped. There is no `G4733` row in the PY2026 V28 file. Look the card up / no PY2026 V28 file row. Do not invent an HCC.

The live E66.2 card: OSA may coexist and should be coded separately if documented as a distinct condition. That does not turn G47.33 into OHS. Apnea is not alveolar hypoventilation. Do not select E66.2 from a sleep-apnea row alone.

Historical V24 mapping

E66.2, E66.01, and E66.813 each map to HCC 22 in the CMS-HCC V24 column of the CMS 2025 Midyear/Final ICD-10-CM Mappings. Those rows are historical PY2025 references. They do not change the PY2026 V28 mapping to HCC 48. A missing value on a card is not evidence that a historical mapping does not exist.

The CMS 2026 Rate Announcement completes the V28 phase-in for non-PACE Medicare Advantage. PACE follows a separate transition; do not apply the non-PACE statement to PACE.

What E66.2 needs

The provider must assess morbid (severe) obesity with alveolar hypoventilation this encounter. Inclusion on the live card is OHS / Pickwickian. A BMI value is not enough. A problem-list row is not enough. Do not invent E66.2 from OSA or from a high BMI without that assessment.

The live E66.2 card lists code to identify body mass index (BMI), if known, for adults (Z68.1-Z68.45) or pediatrics (Z68.5-). Look the exact Z68 up. Verified file rows in this desk set that also sit in HCC 48:

`Z6841,48.0,age >= 15,,`

`Z6842,48.0,age >= 15,,`

`Z6843,48.0,age >= 15,,`

`Z6844,48.0,age >= 15,,`

`Z6845,48.0,age >= 15,,`

`Z6856,48.0,,,`

A mapped Z68.4x still pays HCC 48 once with E66.2. It does not open a second 48. Do not invent maps for Z68 codes that have no file row.

The live E66.2 card also lists obesity complicating pregnancy, childbirth and the puerperium, if applicable (O99.21-). Look that obstetric card up. Do not invent an HCC for O99.21- in this desk.

If the encounter also documents acute respiratory failure, look the exact J96 code up. E66.2 itself is still HCC 48. It is not a respiratory payment HCC. The HCC 213 desk is a different leftover.

Review documentation support

An HCC mapping does not establish reportability. Review the full eligible record and apply the official coding, encounter, program and payer requirements. A problem-list row from last year is not enough. See MEAT criteria and problem lists do not validate HCCs. MEAT is the training mnemonic. The authorities are the Official Guidelines and the record from the date of service.

Common misses

1. Coding E66.01 with E66.2. Excludes1 on E66.01. Same HCC 48. Use E66.2 when OHS / Pickwickian is supported.

2. Expecting a respiratory HCC from E66.2. The live card and the file say HCC 48.

3. Treating OSA (G47.33) as OHS. G47.33 is not mapped. It is not alveolar hypoventilation.

4. Stacking E66.813 as a second 48. Same bucket. Nine codes on the 48 card. One category.

5. Mistaking a missing card value for no historical mapping. E66.2, E66.01, and E66.813 map to CMS-HCC V24 HCC 22 in the historical PY2025 file. Check the model and payment year.

6. Selecting E66.2 from BMI alone. The provider must assess OHS / hypoventilation.

Two-minute check

1. Does the note support OHS, Pickwickian, or morbid obesity with alveolar hypoventilation this visit?

2. If yes, assign E66.2. Look that exact code up on HCC Buddy or in the encoder. Expect HCC 48, CNA 0.186.

3. Do not add E66.01. Excludes1.

4. Code G47.33 only if OSA is documented as distinct. Do not invent an HCC for it.

5. Use Additional the BMI Z68 when known. Same 48 if that Z68 maps. Review documentation support under the applicable official rules. Keep historical PY2025 V24 references separate from PY2026 V28.

Related

Disclaimer

This article is for professional and educational use only. It is not coding, billing, legal, or medical advice. Verify every code, HCC map, and guideline section against current official CMS and ICD-10-CM guidance and your payer's policy before you assign it. Reading it creates no provider, patient, or advisory relationship.

By the HCC Buddy Coding Team. V28 mappings and CNA factors from the cited live code pages (CMS-HCC V28 PY2026 model software and ICD-10-CM mapping file). Not medical advice. Not a CMS-HCC model change beyond V28. Not a rewrite of the E66.9 obesity guide. Not an E11.9 leftover. Not an I10 leftover. Not a D59.31 leftover.

Sources

E66.2 (V28 HCC 48 CNA 0.186; inclusion OHS / Pickwickian; BMI Z68 if known; O99.21- if obstetric; historical PY2025 CMS-HCC V24 HCC 22; see the CMS 2025 mapping source above)

E66.01 (V28 HCC 48 CNA 0.186; Excludes1 E66.2; historical PY2025 CMS-HCC V24 HCC 22; see the CMS 2025 mapping source above)

E66.813 (V28 HCC 48 CNA 0.186; historical PY2025 CMS-HCC V24 HCC 22; see the CMS 2025 mapping source above)

G47.33 (V28 not mapped; no PY2026 V28 file row)

HCC 48 (9 codes; CNA 0.186)

Obesity E66.9 guide

CMS 2026 Model Software / Final ICD-10-CM Mappings