The Revenue Commissioners wrote off some €178 million in unpaid taxes last year, including more than €80 million in unpaid VAT and €42.7 million in unpaid PAYE.
The figures are outlined in the annual report of the Comptroller and Auditor General (C&AG), published today.
In total, there were 157,255 write-off cases, of which 145,797 totalled €51 million.
Some 117,000 of these cases involved amounts of less than €100 and some dated back as far as 1966. The rest were pre-1993 and no amount totalled more than €32,000, according to the C&AG report.
The main reason for the Revenue's decision to write off these unpaid taxes was that it was uneconomic to pursue the defaulters.
In 2,236 cases, the defaulters had ceased trading or had no assets and 954 cases were deemed "uncollectable" due to the financial circumstances of the taxpayer.
A total of 972 people were convicted of failing to file tax returns last year, accumulating total fines of €1 million. This represents a slight drop in the number of convictions on the previous year, when 1,050 non-filers were convicted.
Revenue solicitors sent some 9,348 warning letters last year in relation to failure to file returns.