Billing codes · ICD-10-CM code
Z68 BMI codes: the full table and the rules that deny claims
By Javier Alvarez · Updated · 5 min read
| Category | Z68, Body mass index [BMI] |
|---|---|
| Adult codes | Z68.18-Z68.45, ages 20 and older |
| Pediatric codes | Z68.51-Z68.56, ages 2-19 (CDC growth-chart percentiles) |
| Position on the claim | Secondary only |
| Required partner | An associated diagnosis documented by the provider (e.g., E66.x, E66.3, F50.x) |
| Pregnancy | Do not assign BMI codes |
| FY2027 change (Oct 1, 2026) | Z68.1 becomes a header; new Z68.18 (≤18.4) and Z68.19 (18.5-19.9) |
Dietitians measure BMI at almost every weight-related visit, so Z68 codes end up on a lot of nutrition claims. They're also behind one of the most common one-field rejections we see: a BMI code billed alone, billed first, or billed with a code that no longer exists.
What changed on October 1, 2026 (FY2027)
The FY2027 ICD-10-CM update split the underweight adult code:
| Visit date | BMI under 20, adult | Billable code |
|---|---|---|
| Through Sept 30, 2026 | 19.9 or less | Z68.1 |
| From Oct 1, 2026 | 18.4 or less | Z68.18 |
| From Oct 1, 2026 | 18.5-19.9 | Z68.19 |
From October 1, 2026, Z68.1 is a header, not a billable code. A claim with Z68.1 and a date of service on or after that day will reject as invalid, even if you created the claim template last year. The code set follows the date of service, not the day you submit. A September 30 visit billed in October still uses Z68.1.
No other Z68 code changed in FY2027.
Adult BMI codes (age 20 and older)
| Code | BMI | Code | BMI |
|---|---|---|---|
| Z68.18 | 18.4 or less (from 10/1/2026) | Z68.32 | 32.0-32.9 |
| Z68.19 | 18.5-19.9 (from 10/1/2026) | Z68.33 | 33.0-33.9 |
| Z68.20 | 20.0-20.9 | Z68.34 | 34.0-34.9 |
| Z68.21 | 21.0-21.9 | Z68.35 | 35.0-35.9 |
| Z68.22 | 22.0-22.9 | Z68.36 | 36.0-36.9 |
| Z68.23 | 23.0-23.9 | Z68.37 | 37.0-37.9 |
| Z68.24 | 24.0-24.9 | Z68.38 | 38.0-38.9 |
| Z68.25 | 25.0-25.9 | Z68.39 | 39.0-39.9 |
| Z68.26 | 26.0-26.9 | Z68.41 | 40.0-44.9 |
| Z68.27 | 27.0-27.9 | Z68.42 | 45.0-49.9 |
| Z68.28 | 28.0-28.9 | Z68.43 | 50.0-59.9 |
| Z68.29 | 29.0-29.9 | Z68.44 | 60.0-69.9 |
| Z68.30 | 30.0-30.9 | Z68.45 | 70 or greater |
| Z68.31 | 31.0-31.9 |
The tabular list says adult codes are for persons 20 years of age or older. Some references online say 21. The code set says 20.
Pediatric BMI codes (ages 2-19)
Pediatric codes use BMI-for-age percentiles from the CDC growth charts, not the raw BMI:
| Code | BMI-for-age |
|---|---|
| Z68.51 | Less than 5th percentile |
| Z68.52 | 5th to less than 85th percentile |
| Z68.53 | 85th to less than 95th percentile |
| Z68.54 | 95th percentile to less than 120% of the 95th percentile |
| Z68.55 | 120% to less than 140% of the 95th percentile |
| Z68.56 | 140% of the 95th percentile or greater |
Z68.55 and Z68.56 were added in the FY2025 update (October 1, 2024), and Z68.54 was narrowed at the same time. Before that, Z68.54 meant "95th percentile or greater." Some payer code lists still show the old wording, so check what your payer's policy expects. UnitedHealthcare's preventive policy, for example, lists Z68.54, Z68.55 and Z68.56 for high BMI in children.
The rule: Z68 is always secondary, and never alone
Three rules from the Official Guidelines cover most Z68 denials:
- Secondary only. Section I.B.14 says BMI codes should only be reported as secondary diagnoses.
- Needs an associated diagnosis from the provider. The Z68 note in Section I.C.21 says BMI codes should only be assigned when there's an associated, reportable diagnosis, such as obesity or anorexia, documented by the patient's provider.
- Not in pregnancy. Don't assign BMI codes during pregnancy. For obesity in pregnancy, the provider's O99.21- code carries the information.
One more detail: if the BMI documented during the encounter fluctuates, code the most severe value.
Who may document the BMI (the dietitian can)
Section I.B.14 is one of the few places where the guidelines name dietitians. BMI is one of the values that can be coded from documentation by clinicians other than the patient's provider, and the guideline's example is that "a dietitian often documents the BMI."
So your measured height, weight and BMI can support the Z68 code. The diagnosis it modifies (overweight, obesity class, anorexia nervosa) still has to come from the referring or treating provider. If your note shows a BMI of 36 but the referral only says "nutrition counseling," ask the provider's office for the diagnosis before you bill.
Pairing Z68 with obesity codes
The E66 category tells you to add a Z68 code for BMI, if known. Typical adult pairings:
| Provider's diagnosis | Usually seen with | Notes |
|---|---|---|
| E66.3 Overweight | Z68.25-Z68.29 | Many preventive policies also want a cardiovascular risk factor |
| E66.811 Obesity, class 1 | Z68.30-Z68.34 | Class codes need the provider to document the class |
| E66.812 Obesity, class 2 | Z68.35-Z68.39 | |
| E66.813 Obesity, class 3 | Z68.41-Z68.45 | If class 3 and morbid obesity are both documented, only E66.813 is coded |
| E66.9 Obesity, unspecified | Any Z68.30+ | Works, but the class code is more specific when documented |
| F50.x Eating disorder | Any Z68 value, often low | The guidelines name anorexia as a valid associated diagnosis |
These ranges are typical, not rules. Code the class the provider documented and the BMI you measured, even if they don't line up the way this table suggests. The obesity codes themselves are covered on the E66 obesity codes page.
How payers use Z68 codes
BMI codes often decide whether a visit counts as preventive:
- UnitedHealthcare (MP.016.59, eff. 7/1/2026) lists Z68.30-Z68.45 in its adult obesity row, and Z68.25-Z68.29 with E66.3 under cardiovascular risk. MNT codes 97802-97804 in those rows need one of the listed diagnoses.
- Aetna (CPB 0049) lists Z68.30-Z68.45 as covered, and Z68.25-Z68.29 only for adults who also have cardiovascular risk factors (hypertension, dyslipidemia, impaired fasting glucose or metabolic syndrome).
Payers use the BMI to decide eligibility, but that doesn't change the coding rule. The BMI code still goes after the provider's diagnosis. If a policy says "BMI 30 or greater," it means Z68.3x on the claim with the obesity diagnosis, not instead of it.
Denials when Z68 is alone or first
| What you'll see | Cause | Fix |
|---|---|---|
| Rejection: invalid diagnosis code | Z68.1 on a date of service from Oct 1, 2026, or a header like Z68.3 | Use the complete code: Z68.18/Z68.19, Z68.33, etc. |
| Rejection or CO-16 | Z68 listed first, or it's the only diagnosis | Put the provider's diagnosis first; point the service line at it |
| CO-11 (diagnosis inconsistent with procedure) | Service line points only to the Z68 code | Point 97802/97803 at the medical diagnosis |
| CO-167 (diagnosis not covered) | Obesity/BMI claim on a plan that excludes weight management | Check the plan's exclusions; see preventive vs. medical benefits |
| Records request, then take-back | Z68 on the claim with no height, weight or BMI in the note | Document the measurements at every visit that carries a Z68 code |
For the broader denial patterns, see why nutrition claims get denied. Z71.3 + Z68 is its own common case, covered on the Z71.3 page.
Documentation checklist
- Height and weight measured (or reliably reported) at the visit, and the calculated BMI.
- For ages 2-19: the BMI-for-age percentile and the growth chart used.
- The associated diagnosis in the provider's documentation (the referral, the chart, or a signed order).
- No Z68 code on any claim for a pregnant patient.
With those in the note, the BMI code on the claim can be traced back to a measurement and to a provider's diagnosis.
For the other diagnosis codes on nutrition claims, see the ICD-10 codes for dietitians reference.