Overpaid housing benefit still to be returned to Dundee City Council totals more than £4.2 million.
New figures released by the Department of Work and Pensions show the local authority has managed to slightly lower the amount it is owed since April last year.
But, in September, it still had a bill of £4.227m outstanding, and there was £174,000 written off altogether by the council.
The DWP statistics show there were more than 600 cases referred to the local authority’s fraud investigation, and 20 prosecutions were secured.
During that period, they also took forward 15 prosecutions and imposed penalties on five more people.
Council leader Ken Guild said the authority was determined to recover as much of the cash as possible.
“Those who are deliberately withholding payment are costing the council and that affects our services to the whole of the city,” he said.
“We are not pursuing those whose arrears are purely and simply caused by the ‘bedroom tax’, provided they are making an effort to repay it.”
Mr Guild said an upcoming meeting of the policy and resources committee could see more staff tasked with reclaiming the lost funds.
He added that the council efforts would go forward in a “non-aggressive way”, and added: “We only prosecute as a last resort.”
In November, the council’s director of corporate services Marjory Stewart said more overpayment had been identified as a result of increased targeting of serious fraud cases by the local authority and the DWP.