Figures from the Revenue show that the tax body has so far collected a total of just under €2.5 billion from a number of special investigations.
In its preliminary results for 2008, Revenue said it had taken in €54.6m from these investigations last year, including €29m from a probe into offshore assets. An investigation into money invested in life assurance products yielded €18.7m last year, while there was just over €4m from bogus non-resident accounts.
The figures also show that €60,000 was collected last year as a result of investigations arising from tribunals.
Revenue said it carried out more than 13,000 audits last year, which yielded €570m in tax revenue.
There were 20 convictions for tax evasion last year, while there were another 433 prosecutions in areas such as laundered oil and vehicle registration tax offences.
The Revenue figures also show that cocaine and heroin worth an estimated €517m was seized last year, while cigarettes worth €54.3m were seized.