Per Section 4.1 (a) of the GIS Operating Rules:
Each Retail LSE in the New England Control Area shall register for one Certificate account with the GIS Administrator and for at least one Retail Subaccount for each state in which it does business as a Retail LSE (regardless of whether such Retail LSE is subject to any Attribute Laws in such state) and for any external sales of Energy. In addition, if a Retail LSE provides Energy to a retail load-serving entity that is not a NEPOOL Participant (a “Non-Participant LSE”), such Retail LSE shall register for a separate subaccount for the Energy provided to such Non-Participant LSE.