Rates totalling more than £142 million went unpaid in Northern Ireland over the last year.
Around a tenth of all domestic and commercial rates were not collected, although the figure has been falling in recent years.
Over the last three years the debt has totalled nearly half a billion pounds.
The figures were released in response to an assembly question by the DUP's Keith Buchanan and come just days after finance minister Máirtín Ó Muilleoir proposed a major review of the rates system.
Under the plans, a 4 per cent discount for early payment of household rates would be phased out and a cap on bills for properties worth more than £400,000 would be removed.
The small business rate relief scheme would also be refocused with a £22m fund for a smaller number of retail and hospitality businesses and charity shops would become liable for rates.
However, the DUP has warned the proposals do not have Executive approval.
The Department of Finance's Land and Property Services (LPS) collects rates and failure to pay a bill can potentially result in court action, fines and even jail time.
In response to the figures, Mr Ó Muilleoir said it was accepted that many ratepayers struggle to keep on top of their bills.
"I can assure you that LPS takes a serious view of non-payment of rates and rigorously pursues all debt," he said.
"However, this must be balanced against assisting ratepayers who are genuinely struggling and require some additional flexibility to help pay their rate bills.
"LPS continues to provide significant support in the form of exemptions, relief and allowances paid both to domestic and non-domestic ratepayers.
"While LPS will make efforts to support those who are struggling to pay, the must, and will, rigorously pursue those who don't pay.
"Where ratepayers fail to pay or do not enter into payment arrangements or break those arrangements, LPS will take court action and see to recover the debt through the Enforcement of Judgements Office or will instigate bankruptcy proceedings."
The Sinn Fein minister also pointed out that the amount of unpaid rates has decreased in the past two years.
In 2014/15 it stood at £156m, while in the previous year it was £162m.
However, Mr Buchanan said the high amounts of unpaid rates were "concerning".
"This is a significant amount of money that is not currently available to fund front-line services for the public," he said.
"It is positive to note that the figure has dropped by £20m over the last two years and I would hope that this figure continues to fall in coming years.
"Whilst this figure is concerning it does not mean that LPS will not receive it. The most important figure will be the amount of debt that is written off by LPS and whether that is decreasing also."
