Manx Care has been told to redo a Freedom of Information request after taking four months to respond.
The health authority was asked for correspondence about the Roundhouse community hub in Braddan in April 2024.
Under the law, it should have replied within 20 working days but only eventually responded in August.
When the information was released, large parts had been blacked out. No explanation was given to the person who made the request about why this was done or how they could appeal.
The Information Commissioner said Manx Care had “failed to evidence that a reasonable search had been undertaken” and had applied exemptions without properly checking what information it held.
The Commissioner also found the authority had breached the law by not providing a refusal notice and by failing to give progress updates despite repeated requests.
Manx Care later said it should have explained that the redactions were made to protect personal data.
The Commissioner has ordered the authority to carry out fresh searches and issue a new response within 30 days.