Check Out ICD-10-CM Coding Guideline Updates for FY 2026
New updates affect specific conditions and some bigger-picture coding conventions. The U.S. Department of Health and Human Services (HHS) agencies Centers for Medicare & Medicaid Services (CMS) and the National Center for Health Statistics (NCHS), have released the official guidelines for ICD-10-CM coding and reporting for fiscal year (FY) 2026, which go into effect Oct. 1, 2025. The guidelines say: “These guidelines are a set of rules that have been developed to accompany and complement the official conventions and instructions provided within the ICD-10-CM itself. The instructions and conventions of the classification take precedence over guidelines.” Keep reading to see which conditions have been affected by guideline updates or changes. Find New Guidance on Multiple Sites Coding ICD-10-CM has added guidance defining multiple sites, explaining that the term involves two or more sites. According to the new guidance, if there are chapter-specific guidelines for assigning codes for multiple sites, coders should follow those. If there aren’t any chapter-specific guidelines, then coders should assign codes according to the specific, individual sites when documented. If the specific sites aren’t documented, coders should assign the appropriate code for multiple sites. Look for This Comprehensive Overhaul of HIV Reporting Guidelines The biggest revision to the ICD-10-CM guideline changes involves the way you will select and sequence human immunodeficiency virus (HIV) codes. CMS and NCHS have made numerous changes to guideline I.C.1.a.2, including coding changes for various scenarios involving patients before, during, and after an HIV diagnosis. But many also make the guideline language more precise by insisting the patient’s HIV status be documented and not simply “known.” The first change involves the insertion of new guideline I.C.2.a.2.(a), which tells you to assign B20 (Human immunodeficiency virus [HIV] disease) when patient documentation indicates acquired immunodeficiency syndrome (AIDS), HIV, “or if the patient is treated for any HIV-related illness or is described as having any condition(s) resulting from the patient’s HIV positive status.” New guideline I.C.2.a.2.(c), resequenced from current guideline I.C.2.a.2.(b), also contains the clarification that B20 can be assigned as a secondary diagnosis for patients with HIV who have been admitted “for an unrelated condition (such as a traumatic injury).” The same is now going to be true for “other documented conditions,” per the guideline revision. CMS and NCHS have also clarified use of Z21 (Asymptomatic human immunodeficiency virus [HIV] infection status). Under the newly revised guideline I.C.2.a.2.(e), you are told to apply the code “When ‘HIV positive,’ ‘HIV test positive,’ or similar terminology is documented, and there is no documentation of symptoms or HIV-related illness.” This reflects a change in the language of the previous guideline, which told you to apply the code “when the patient without any documentation of symptoms is listed as being ‘HIV positive’, ‘known HIV’, ‘HIV test positive’, or similar terminology.” For patients with inconclusive serology of HIV, the new guidelines still tell you to assign R75 (Inconclusive laboratory evidence of human immunodeficiency virus [HIV]); however, the language “but no definitive diagnosis or manifestations of the illness” has been deleted. Similarly, for patients previously diagnosed with HIV, you will continue to assign B20, but now that diagnosis will have to be documented and not “previously known,” per the guideline revision. Another change tells you to assign O98.7 (Human immunodeficiency virus [HIV] disease complicating pregnancy, childbirth and the puerperium) only “when a patient presents during pregnancy, childbirth or the puerperium with documented symptomatic HIV disease or an HIV related illness.” You are also told to assign Z21 (Asymptomatic human immunodeficiency virus [HIV] infection status) for pregnant patients, patients giving birth, and for patients during the puerperium who are either HIV-positive or who have documented asymptomatic HIV. Changes for HIV Testing Encounter Coding and Antiretroviral Medication For new guideline I.C.2.a.2.(i), ICD-10-CM 2026 changes the language change from “If a patient is being seen to determine his/her HIV status,” to “If a patient without signs or symptoms is tested for HIV.” Additionally, for patients with signs and symptoms presenting for testing, you are now told not to report Z11.4 (Encounter for screening for human immunodeficiency virus [HIV]). And last, new guideline I.C.2.a.2.(j) provides revised instructions for reporting HIV-positive patients who are being treated with an antiretroviral medication. Now, you are to assign Z21 “in the absence of any additional documentation of HIV disease, HIV-related illness or AIDS.” Know How to Report Type 2 DM in Remission The ICD-10-CM official guidelines add a new subsection regarding type 2 diabetes mellitus in remission conditions. Starting October 1, under section I.C.4.a.1, you’ll find subsection (b). This guideline instructs you to assign E11.A (Type 2 diabetes mellitus without complications in remission) when the provider’s documentation indicates the diabetes mellitus is in remission. “If the documentation is unclear as to whether the Type 2 diabetes mellitus has achieved remission, the provider should be queried,” the guideline states. An example of when the documentation is unclear would be if the provider wrote the term “resolved,” which is not the same as the condition being in remission. Handle Hypertension With Heart Disease Conditions Section I.C.9.a.1 of the ICD-10-CM official guidelines mentions specific code and code categories related to hypertension with heart conditions that are assigned to a code from the I11.- (Hypertensive heart disease) subcategory. In FY 2026, you’ll find small changes to the code list. In the 2025 code book, the guideline included the following codes for hypertension with heart conditions: When the 2026 ICD-10-CM code book takes effect, this portion of the guideline will change to delete the “or” following I50.- and it only lists I51.4 instead of I51.4-I51.7. Codes I51.89 and I51.9 remain in the guideline. The guideline also includes descriptors for each code mentioned in the text. This paragraph concludes by adding I51.- (Complications and ill-defined descriptions of heart disease) to the instruction, directing you to use additional codes to identify the patient’s heart condition. Next, section I.C.9.a.1 adds direction explaining that hypertension with heart conditions that fall under the codes below will be assigned to a code from the I11.- category: Additionally, the guidelines stating the codes mentioned above are to be reported separately if the provider’s documentation states the conditions are unrelated to the hypertension remains unchanged. However, the guideline adds that “The applicable hypertension code I10, Essential (primary) hypertension, or a code from category I15, Secondary hypertension, should be assigned.” In section I.C.9.a.3, the code book moves the following sentence to the beginning of the section: “The codes in category I13, Hypertensive heart and chronic kidney disease, are combination codes that include hypertension, heart disease and chronic kidney disease.” The guideline goes on to instruct you to use I13.- codes to report cases of hypertension with both heart disease and chronic kidney disease. List These Dx Codes First for Prophylactic Organ Removal ICD-10-CM has also issued guidance for encounters when a physician performs prophylactic removal of an organ, such as removal of the breasts due to a family history of cancer. For these types of prophylactic removals, the principal or first-listed code should be a code either from the Z40.0- (Encounter for prophylactic surgery for risk factors related to malignant neoplasms) code set or Z40.8 (Encounter for other prophylactic surgery). Note: “If applicable, assign additional code(s) to identify any associated risk factor (such as genetic susceptibility or family history),” reports ICD-10-CM. The updated guidelines have also cleared up how to report diagnoses “if the patient has a malignancy of one site and is having prophylactic removal at another site to prevent either a new primary malignancy or metastatic disease.” When this occurs, “a code for the malignancy should also be assigned in addition to a code from subcategory Z40.0-,” reports ICD-10-CM. However, you should not assign a Z40.0- code “if the patient is having organ removal for treatment of a malignancy, such as the removal of the testes for the treatment of prostate cancer.” Check Out These Clarifications on Antineoplastic Therapy Dx ICD-10-CM has issued more explicit directions for patient admissions/encounters that are mainly for administration of antineoplastic chemotherapy, immunotherapy, and radiation therapy. When the main purpose of the encounter is to administer chemotherapy, immunotherapy, or external beam radiation therapy to treat a neoplasm, assign one of the following codes as the first-listed diagnosis, depending on encounter specifics: When a patient is seeing the physician for more than one kind of antineoplastic therapy in the same session, you can report more than one diagnosis code. “If the reason for the encounter is more than one type of antineoplastic therapy, code Z51.0 and codes from subcategory Z51.1- [Encounter for antineoplastic chemotherapy and immunotherapy] may be assigned together, in which case one of these codes would be reported as a secondary diagnosis,” ICD-10-CM reports. Additionally, “the malignancy for which the therapy is being administered should be assigned as a secondary diagnosis.” There are other times that you should list the malignancy itself and no other diagnosis code. “If a patient admission/encounter is for the insertion or implantation of radioactive elements (e.g., brachytherapy) the appropriate code for the malignancy is sequenced as the principal or first-listed diagnosis. Code Z51.0 should not be assigned,” per ICD-10-CM. Assign BMI Codes Only When Relevant ICD-10-CM has added guidelines for situations in which coding a patient’s body mass index (BMI) is considered appropriate. The guidance says that for code Z68 (Body mass index [BMI]), “BMI codes should only be assigned when there is an associated, reportable diagnosis (such as obesity or anorexia) documented by the patient’s provider.” The guidance also says that BMI codes should not be assigned during pregnancy. If a patient pursues an encounter for an associated reportable condition and the documentation shows that the patient’s BMI fluctuates, coders should assign a code reflecting the most severe value, according to the updated guidance. Revenue Cycle Insider Editorial Team
