Belong Atherton offers 26 self-contained apartments for independent living.
The company has maintained its 'Outstanding' rating for four out of five areas after its first inspection in 2016.
CQC
The Croydon-based service cares for people with learning disabilities and mental health problems.
The provider failed to carry out DBS checks on its staff, some of whom lack any qualifications, CQC inspectors found.
In the letter to the Commons, CQC said the decision was “disappointing”, given the programme has demonstrated.
The Oxfordshire-based company achieved the rating for being well-led and effective.
Westmorland Homecare in Kendal was deemed 'Outstanding' in all five inspection categories.
The service was praised for its exceptional leadership throughout the report.
The provider was rated 'Outstanding' by the commission during an inspection in October.
The service has been placed in special measures after the CQC found “multiple breaches” relating to safe care and treatment.