More than 5,000 blue badges for disabled motorists were registered to dead people in NI, the Audit Office has said.
The details have emerged in a new report by NI auditor general Kieran Donnelly.
He said £11m of fraud, error and over-payments had been identified following consideration of the National Fraud Initiative (NFI).
It is believed total savings from the initiative may eventually exceed £16m.
The report was on the first application of the auditor general's new powers in relation to the NFI.
It found that by September 2010 housing benefit over-payments of £2.2m and 2,240 cases of suspected fraud had been identified. It is projected that over-payments will rise by a further £1.5m.
Almost £8.4m in savings involving non-payment, fraud and error have so far been identified in domestic rates and it is projected that figure will rise by a further £3.2m.
A total of 5,142 blue badges issued to those with severe mobility problems and which give entitlement to parking concessions were registered to dead people.
Suspected fraud, error and overpayment of £729,000 was found involving pension payments.
A total of £209,000 was overpaid to suppliers.
In his report, Mr Donnelly looked at the NFI for 2008/09. In some cases the investigations are still ongoing and the report gives the position as at September 2010 for cases still to be finalised.
Seventy-four public bodies in Northern Ireland took part in the NFI exercise.
'Public sector fraud'
Mr Donnelly said he was keen to explore how Northern Ireland could further develop and widen its involvement in NFI.
"I therefore welcome all approaches by both public and private sector bodies highlighting potential datasets that will help expose and reduce public sector fraud," he said.
The report has also identified opportunities for gaining greater benefit from another NFI initiative under way for 2010/11.
These included prioritising and following up data matches and considering whether the quality of records can be improved.
"Although the roll out of NFI in Northern Ireland has been very successful, I believe that there is considerable scope to further exploit the potential of data matching," he added.