As of yesterday, October 1, 2023, every claim with a date of service on or after that day must use the FY 2024 ICD-10-CM code set. The update brings 395 new codes, 25 deletions and 13 revisions. Practices that ran the update in September are watching their first rejections this week. Practices that did not are about to find out which of their favorite codes stopped existing.
This is the annual update that gets less attention than the CPT changeover because there is no fee attached to a diagnosis code. That is a mistake. A deleted diagnosis code on a claim is a rejection at the clearinghouse, and a truncated code (a valid code that now requires a further character) is a denial for an invalid diagnosis. Both are avoidable with an afternoon of work.
Key takeaways
- FY 2024 ICD-10-CM applies to dates of service from October 1, 2023: 395 new codes, 25 deletions, 13 revisions. September visits billed in October still use FY 2023 codes.
- About half the new codes are Chapter 20 external cause codes; the rest add clinical specificity that primary care and several specialties will use daily.
- The social determinants of health Z codes grew again, including new custody and caregiver noncompliance codes. Report them as secondary diagnoses now, even where nobody pays for them yet.
- Read the clearinghouse rejection report every morning through mid-October, fix templates and favorites, and end-date deleted codes rather than removing them.
What is in the FY 2024 update
| Area | What changed | Who it affects most |
|---|---|---|
| Chapter 20, external causes of morbidity | About 123 new codes, close to half of all additions, largely describing how injuries occurred | Urgent care, orthopedics, emergency settings, pediatrics |
| Chapter 21, factors influencing health status (Z codes) | Around 30 new codes, including social determinants of health additions and long-term drug use codes | Primary care, behavioral health, pediatrics, anyone reporting SDOH |
| Clinical chapters | New specificity for Parkinson's disease, resistant hypertension, insulin resistance and metabolic syndrome, sickle cell disease and others | Primary care, neurology, endocrinology, cardiology, hematology |
| Deletions and revisions | 25 codes deleted (mostly replaced by more specific codes); 13 descriptors revised | Everyone: check the top 100 codes against the deletion list |
The clinical codes an office practice will actually use
Most of the attention goes to the external cause codes because there are so many of them. For an office practice, the smaller group of clinical additions matters more, because they replace codes providers select every day.
| New code or family | Describes | What changes in the note |
|---|---|---|
| I1A.0 | Resistant hypertension | Document the medications tried and that pressure remains above goal despite them |
| E88.810, E88.818, E88.819 | Metabolic syndrome, other insulin resistance, insulin resistance unspecified | Name the condition rather than listing its components separately |
| G20.A1, G20.A2, G20.B1, G20.B2, G20.C | Parkinson's disease with or without dyskinesia and with or without fluctuations | Record dyskinesia and motor fluctuations explicitly; G20 alone is no longer a complete code |
| Z79.85 | Long-term use of injectable non-insulin antidiabetic drugs | Distinguish GLP-1 agonists and similar injectables from insulin (Z79.4) and oral agents (Z79.84) |
| Z79.6- | Long-term use of immunomodulators and immunosuppressants, by class | Name the drug class in the medication list |
| Z62.23, Z62.24 | Child in custody of a non-parental relative; child in custody of a non-relative guardian | Record the living and custody arrangement when it is relevant to care |
| Z91.A4, Z91.A5, Z91.A9 | Caregiver's noncompliance with the patient's medication regimen, renal dialysis, or other treatment | State that it is the caregiver, not the patient, who is not following the plan |
The Parkinson's change is the one most likely to produce rejections in neurology and primary care, because G20 was a complete three-character code for years and now requires the fifth character. Any favorites list or template that still carries plain G20 will fail at the clearinghouse.
The social determinants of health codes
Category Z62, problems related to upbringing, gained new codes that identify the child's caregiving situation more precisely, including Z62.23 (child in custody of non-parental relative) and Z62.24 (child in custody of non-relative guardian), along with codes describing conflict between a child and a non-parental relative or guardian. The Z91.A subcategory for caregiver noncompliance was made more granular as well, with codes such as Z91.A4 (caregiver's other noncompliance with patient's medication regimen), Z91.A5 (renal dialysis) and Z91.A9 (other medical treatment and regimen).
SDOH Z codes carry no direct payment in most fee-for-service contracts, but they feed risk adjustment discussions, quality programs, and the community health integration services CMS proposed to pay for in the CY 2024 Physician Fee Schedule. Practices working toward or maintaining PCMH recognition already screen for social needs; coding the results is how the screening becomes visible in claims data. We think most primary care practices should be reporting these codes now, even where nobody pays for them yet. Payers building value-based contracts ask for this data, and a practice with two years of it negotiates from a different position than one starting from zero.
External cause codes: pick your level of effort
Half the update is Chapter 20. For most office practices, the honest answer is that external cause codes are reported when the payer or state requires them and otherwise are secondary. Urgent care and orthopedic practices should review the new codes in the categories they bill. Everyone else should confirm their templates do not force an external cause code that no longer exists. Where a template demands one, a provider will pick the nearest thing on the list, and the nearest thing is often a deleted code.
The two-week claim check
Whether or not you updated on time, do this now.
- Run the clearinghouse rejection report daily through October 16. Filter for diagnosis code rejections. Each one is a code that was deleted or now needs more characters.
- Pull the top 100 diagnosis codes by frequency for the last twelve months. Check each against the FY 2024 addenda. Any deleted or revised code gets its replacement noted and its template updated.
- Check the favorites lists. Providers keep personal favorites in the EHR. A deleted code in a favorites list will be selected on autopilot until someone removes it.
- End-date, do not delete. Codes valid through September 30 must remain in the system for September dates of service, corrected claims and appeals. Set the end date to September 30, 2023.
- Confirm the EHR and the practice management system are both updated. When they run separate code tables, one of them is often a version behind, and the interface passes a code the billing side rejects.
Where the rejections will come from
In past October updates, the diagnosis rejections we see in the first two weeks fall into three groups. Deleted codes still sitting in EHR favorites and superbill templates. Codes that were expanded and now require a fifth, sixth or seventh character, submitted at the old length. And interface mismatches where the EHR accepted the new code but the practice management system's table had not been updated, so the claim failed at scrubbing. The first two are fixed at the template level; the third is a vendor call. All three show up on the clearinghouse rejection report, which is why we ask practices to read it every morning until mid-October.
Rejections are the visible problem. The invisible one is the claim that goes through with a less specific code because the provider could not find the new one. Nothing rejects, nothing denies, and the practice's data quietly gets worse. The fix for that is the provider bulletin described next, not the rejection report.
Documentation, not just codes
New specificity in the code set is only usable if the note contains the detail. If a new code distinguishes laterality, encounter type or a specific caregiver relationship, the provider has to write it down. Coders cannot infer. A short provider bulletin listing the handful of new codes relevant to the specialty, each with the documentation element it requires, is worth more than a link to the full addenda.
A worked example. A pediatric practice we work with screens every well visit for social needs. Before October, a child living with a grandparent under a custody arrangement was coded with a general Z62 code that said little. Under FY 2024 the encounter carries Z62.23, and the practice's quarterly report of SDOH findings, which it shares with its payer under a value-based arrangement, now distinguishes custody situations from other upbringing concerns. Nothing about the visit changed. The data got better, and the practice's case for care coordination resources got stronger.
Questions we hear
Can we use a FY 2024 code on a September date of service?
No. The code set is determined by the date of service (or discharge date for inpatient). A September 28 visit uses FY 2023 codes even if it is billed in October. This is why the deleted codes must stay in the system.
Do payers reject SDOH codes?
Generally no; they are accepted as secondary diagnoses. A few payer systems have historically limited the number of diagnosis pointers or rejected Z codes in the primary position, which is a claim formatting issue rather than a coverage one. Report them as secondary.
Where do coders get trained on the changes?
The official guidelines and addenda are the source. Practices that want a structured session can use the annual update module in the Revelrex live online coding courses, which covers the FY 2024 changes by specialty.
What to do this week
- Read the clearinghouse rejection report every morning and list every diagnosis code rejection with the code that caused it.
- Run the top 100 diagnosis codes for the last twelve months and mark every code that was deleted, expanded or revised for FY 2024.
- Fix the EHR favorites lists and superbill templates for those codes, with the Parkinson's, hypertension and long-term drug use codes first.
- Confirm the FY 2023 codes are end-dated September 30, 2023, not removed, in both the EHR and the practice management system.
- Send providers a one-page bulletin of the new codes for their specialty, each with the documentation element it requires.
