A residential centre for people with disabilities took thousands of euro from residents' private accounts without their consent to fund services which the centre should have been providing.
The revelation by the Health Information and Quality Authority is accompanied by criticism of the Saint John of God Services for appointing a former staff member to investigate the matter.
HIQA said this failed to assure the watchdog that the investigation was independent.
The Greenmount centre, which was the focus of the unannounced HIQA inspection last July, is on the Drumcar campus of the St John of God North East Services in Co Louth.
It was home to 22 residents with intellectual and physical disabilities at the time that HIQA received a tip-off alleging that residents were inappropriately charged for services and equipment which should have been supplied by the service provider.
The inspection report, published today, says the concerns were substantiated and that the practices had taken place over a prolonged period of time.
It underlines that there was an absence of consent or consultation for the charges and that concerns remained with regard to the safeguarding of residents' finances.
Inspectors found that between 2012 and 2016 a number of residents were charged €2,300 each for the cost of specialised armchairs.
Another resident was charged €2,500 for an armchair and a dexa - or bone density - scan.
Another, who was assessed as needing a body brace, was charged €552 for the appliance.
The inspectors were told an investigation into the matter was under way but they say the person conducting the review had been on the staff of the St John of God Services and that, therefore, HIQA was not assured that the investigation was sufficiently independent.
In a statement Saint John of God Community Services said it fully accepts HIQA's findings.
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It adds that the practice of residents, as they put it, "purchasing" personalised equipment and aids for their own use ceased at Greenmount last year.
The charity also says a process of reimbursing residents was under way when HIQA conducted its inspection.
It says that in August 2015, 11 months prior to the HIQA inspection, St John of God North East Services commenced an independent review of residents' finances backdated to 2013.
"Where it was identified that residents had purchased their own item of medical/specialised equipment/aids for their personal use, the Service had either reimbursed residents or was in the process of doing so, at the time of the unannounced monitoring inspection in July of this year. HIQA Inspectors acknowledge this review and noted evidence of residents being reimbursed when they conducted the inspection in July," the statement says.
Following a review, the services say they are "confident that robust financial governance is now in place, relating to the safeguarding of residents' finances".
The charity has also said it is still trying to establish whether the practice has existed in its nationwide network.