Limited access to some SW computer systems is granted to certain HSE staff in areas such as Medical Cards, Drug Payment Scheme (to check and verify PPSNs), Nursing Home Subventions (to verify SW pension income), and other areas as agreed between HSE and Dept of Social & Family Affairs. I wouldn't be aware of any areas which would require specific access to claim details of Rent & Mortgage Supplement.
All requests for access to the system are made in writing, and all staff who access the system for their work are made aware of their commitments under Data Protection.