LOTTO chiefs opposed a suggestion to tax big jackpot wins - which could have raised more than €9m a year - arguing that it would be "detrimental" to sales and profits.
Dublin Labour TD Sean Kenny raised the idea in a parliamentary question.
Documents released by the Department of Public Expenditure and Reform (PER) include calculations by Lotto staff that show that prizes of €750,000 or more - including the Irish Lotto and the Euromillions - totalled €184.8m in 2014.
A 5pc tax on these prizes would have pulled in €9.2m.
While providing the calculations the Lotto's head of finance Declan Harrington also expressed opposition to the proposal, shortly after the private company, Premier Lotteries Ireland (PLI), took over the running of the game.
"The introduction of such a tax would have a significant detrimental impact on sales of National Lottery games and on the profits of Premier Lotteries Ireland as licensee.
"The introduction of such a tax was not referred to in the Licence competition and PLI bid for the licence on that basis," Mr Harrington wrote to a PER official last January.
A Finance spokesman told the Herald that there are no plans to introduce a tax on Lotto wins.
Dublin North East TD, Mr Kenny said he still believes taxing Lotto wins is "worth considering".
"There is a tax on betting horses and it doesn't seem to stop people going to the races so it's not a very convincing argument," he said.
"I don't think winners would object to it."