SU

HCPCS Level II modifier that may be used with CPT or HCPCS Level II codes indicating procedure performed in a physician’s office (to denote use of facility and equipment).

Subcapitation

Situation in which an organization using a capitated method of payment contracts with other providers on a capitated basis and shares a part of the original capitated premium (e.g., carve out services).

Subcategory

1. Fourth digit of a diagnostic code in ICD-9-CM that further defines a three-digit category such as site, cause, or other characteristics. 2. Division under a category in the Current Procedural Terminology (CPT) code book.