Yes, it is mandatory for onboarding and P2P for the Mitie entities which are live as below:

B002 – MITIE Landscapes Limited G000 – MITIE Shared Services Limited
B012 – MITIE Cleaning & Environmental Services Limited G002 – MITIE Shared Services Limited
F001 – MITIE Aviation Security Limited G094 – MITIE Treasury Management Limited
F002 – MITIE Security Limited G097 – The MITIE Foundation
F007 – UK CRBS Limited G100 – MITIE Group PLC
F008 – Procius Limited K001 – MITIE Care and Custody Limited
F014 – Global Aware Intrnl Ltd K005 – Care & Custody (Health) Limited