Almost £33 million of actual and potential fraud has been stopped in Northern Ireland by comparing official records, the audit office said.
Housing benefit, pensions and rates evaders were among the main culprits caught by matching data from different organisations.
They included cases where the Housing Executive was paying benefits to a sole occupier, unaware that another person was living there and registered at that address with another government body.
One person lived with a partner at a property but failed to tell housing authorities and netted an extra £57,000 over five years, according to a report on the National Fraud Initiative (NFI).
Another did not declare a pension or a partner and fraudulently earned an extra £33,000 in benefits.
One offender worked for a public sector organisation while claiming housing benefit and jobseeker’s allowance over six years. Another was receiving housing payments for two properties but left one of them in 2010.
Auditor general Kieran Donnelly said: “Fraud impacts on the level of funding available for frontline services, so fighting fraud must remain a key element in ensuring that limited public funds for the provision of goods and services are maximised.
“Fraud affects us all and we all pay the price.”
He said the NFI had detected fraud to the value of almost £33 million. The major checking procedure has been run four times and the money recovered represents current and past wrongdoing stopped and potential future crime averted.
Between April 2014 and March 2016 more than £3.1 million of fraud and error was detected through data matching.
Housing benefit fraud and overpayment amounted to more than £1.2 million. Suspected fraud, error and overpayment of pensions was worth more that £1.4 million.
More than 60 cases of rates evasion valued above £330,000 were detected.
There were more than 4,000 matches between blue badges, which entitle the disabled to use parking spaces for free, and death records, usually meaning the document was not returned after the holder had died and could be used fraudulently.
Similarly, there were almost 2,500 matches between concessionary travel pass holder records and death records.