It’s That Time Again: Preparing for the New ICD-10-CM Codes

Written By Lisa Selman-Holman, VP of Clinical Services, McBee

As we approach October 1, it’s time for our annual reminder: new ICD-10-CM codes go into effect for encounters beginning October 1, 2025. This means that any visit occurring on or after October 1 must reflect the updated codes on the claim.

What This Means for Billing

• Billing periods that begin September 1 and end October 1 may span both code sets.
• If any visit (line item) occurs on or after October 1, the entire claim must reflect the new codes.
• Claims submitted with outdated codes for visits on or after October 1 will be rejected.
• Agencies have two options:
  1. Update the codes before submitting the claim, or
  2. Wait for the claim to be rejected, then correct and resubmit with the updated codes.

Some agencies choose the latter, but proactive updating can reduce delays in reimbursement.

What If There Are No October Visits?

If the billing period extends into October but no visits occur on or after October 1, there is no need to update the codes. The claim can be submitted using the current code set.

Using Codes That Are No Longer Valid

Example: Multiple Sclerosis

Let’s say Mr. Goodwin has a diagnosis of Multiple Sclerosis (MS). His billing period includes visits on October 1 and October 4. The diagnosis code G35, carried over from a September 5 recertification, is no longer valid for MS as of October 1. Without further documentation, Mr. Goodwin’s new diagnosis is G35.D. The agency must either:

• Update the code before billing, or
• Submit the claim, allow it to be rejected and then correct the code.

MS will be one of the more problematic diagnoses this year because G35 will be invalid for dates of service on or after October 1.

Other Diagnoses: Less Risky, Still Important

Some new codes, like those for inflammatory breast cancer (IBC), will not cause claim rejections if miscoded. For example:

• Before October 1: IBC is coded under C50.-.
• After October 1: IBC should be coded under the new C50.A- series.

If the agency continues to use the old code after October 1, the claim won’t be rejected because the C50.- code is still valid, but the coding will be incorrect for IBC and should be corrected as soon as possible.

What About Hospice?

Just like in home health, hospice claims must reflect the updated ICD-10-CM codes for any services provided on or after October 1. This applies to all levels of care—routine home care, continuous home care, inpatient respite and general inpatient care.

Here’s what that means in practice:

• If any date of service on a hospice claim falls on or after October 1, the entire claim must use the updated diagnosis codes.
• If the claim includes only dates of service prior to October 1, the current (pre-October 1) codes remain valid.
• Claims that include outdated codes for dates of service on or after October 1 will be rejected and must be corrected and resubmitted.

This is especially important for longer hospice benefit periods that span the transition date. Even if the terminal diagnosis hasn’t changed, if the code has been updated or replaced, it must be reflected on the claim for any October dates of service. This applies to codes for comorbidities, too.

CMS Official Statement

“These 2026 ICD-10-CM codes are to be used for discharges occurring from October 1, 2025 through September 30, 2026 and for patient encounters occurring from October 1, 2025 through September 30, 2026.” (Note: The discharge portion of this statement does not apply to home health or hospice.)

The CMS ICD-10-CM Code files are ready for download: ICD-10 | CMS

Need a new 2026 ICD-10-CM coding manual? Order now at a discounted rate on McBee Post-Acute Academy.

Want a deeper dive into the FY2026 ICD-10-CM updates? Watch our on-demand webinar to explore key changes, coding implications and expert guidance for staying compliant.