Modifier XU

XU belongs to the X{EPSU} family, four HCPCS modifiers CMS created under Change Request 8863, effective January 1, 2015, to split modifier 59 into narrower subsets. XE covers a separate encounter on the same date, XS a separate organ or structure, XP a different practitioner, and XU a service that stands apart because none of its work duplicates what the main procedure usually includes. CMS asks for the matching X modifier in place of 59 whenever one fits, and allows it on either code of an NCCI pair. CMS may also require a specific X modifier for code pairs at high risk of incorrect billing, and contractors may insist on the X modifiers in place of 59 for local program integrity reasons.

CMS’s modifier booklet limits XU, like 59, to narrow situations. A diagnostic procedure performed before a therapeutic one can stand alone when it is the basis for deciding to proceed, comes first without being mixed into the therapeutic work, and is not something the therapeutic procedure would have required anyway. A diagnostic procedure performed after a completed therapeutic one can stand alone when it is not a common, expected or necessary follow-up.

The misuse CMS names is reporting XU because the two code descriptors read differently. The codes in an edit pair always describe different procedures; at the same site in the same encounter they stay bundled unless one of the narrow situations above applies. A different diagnosis on each line is not enough either. The record has to show the separation, because an X modifier on the claim is a statement that the services did not overlap.