If you are a both Part-M and 145 organisation, is it also then required that you show your compliance for Part 66?

Yes and No.

Yes, if you maintain Aircraft

No, when you maintain Aircaft Components (including APU and Engines). For this we refer to Article 5, 6. Of the Cover regulation, EU 1321/2014.

“Until specific requirements for certifying staff for components are added to this Regulation, the requirements laid down in the national laws in force in the relevant Member State shall continue to apply, except for maintenance organisations located outside the Union where there quirements shall be approved by the Agency.”

EASA Part 66 is all about licensing of aircraft maintenance staff.
To perform part-145 approved maintenance work or in other words; Able to certify the work (CRS – Certificate of Release to Service) you need Part-66 licensed staff.

A Part-66 Maintenance License is a personal document (like a drivers license) and forms the basis for a company approval. The both form the basis for certification authorisation, issue a CRS.

Second; Part-66 also defines the privileges of the Maintenance License regarding aircraft type and rating (B1 = Airframe , Powerplant. B2= Avionics)