Is it a CC or MCC? FY2026 checker with exclusion logic
Static lists show base status. This checker also applies the FY2026 principal-diagnosis exclusion pairs (768,522 of them), so you see whether the code actually counts on this claim.
Why base status isn't enough
CMS removes CC/MCC credit when a secondary diagnosis is clinically integral to the principal diagnosis — acute kidney failure secondary to end-stage renal disease, for example. These exclusion pairs change every fiscal year and static lists ignore them, which is one reason severity capture audits find both over- and under-coding. Our inpatient CDI engine applies this same table on every chart it reviews.
FAQ
- What is the difference between a CC and an MCC?
- A CC (complication or comorbidity) and an MCC (major complication or comorbidity) are secondary diagnoses that increase MS-DRG severity and payment. MCCs represent substantially higher resource use than CCs. For FY2027 (MS-DRG v44) there are 15,100 CC codes and 3,357 MCC codes.
- Why isn’t a base CC/MCC list enough?
- CMS exclusion logic removes CC/MCC credit when the secondary diagnosis is too closely related to the principal diagnosis. A code that is a CC on one claim can count as nothing on another. FY2027 defines 18,470 exclusion rule sets (33.6 million principal-diagnosis pairs) — this checker applies them.
- Does one MCC always maximize the DRG?
- One MCC generally assigns the "with MCC" severity level in a two- or three-way DRG split, but grouping also depends on the principal diagnosis, procedures, discharge status, and DRG-specific logic. Use a grouper for final assignment.
Want FY2027 change alerts when CMS updates these lists? Watch the tools hub — newsletter signup coming with Phase 2.