The Regulator of the National Lottery has found that operator Premier Lotteries Ireland breached provisions of the legislation and licence in relation to three scratch card games.
However, the watchdog has decided that licence payments should not be withheld from Premier Lotteries Ireland (PLI) over the non-compliance.
The issues related to two scratch card games, Congratulations 186 and Congratulations 223, that operated last year and another, Diamond Bingo Doubler, which ran in 2015.
None of the cards from any of the games are in circulation any more.
In the games, the stated number of top prizes available did not match the number approved for each originally.
Following an inquiry into the matter, regulator Carol Boate found that the prizes were omitted due to human error and inadequate control measures on the part of PLI.
The failures led to three provisions of the National Lottery Act 2013 and PLI's licence with the state being breached.
These include failure to hold three lottery games in accordance with the rules, failures to ensure statements regarding games were true and failures to have an adequate system of internal control to provide assurance of compliance with the relevant provisions of the Act and Licence in regard to successor games.
However, having considered the issues, Ms Boats said she is satisfied that PLI acted transparently and in good faith and that no other lottery games were impacted by the issue.
She also concluded that it has put in place effective controls to prevent the issue arising again and incurred costs in rectifying the issue.
As a result, the watchdog decided withholding licence payments in this instance was not necessary.
According to the regulator, the value of the prizes was returned to players through a New Year's Special Draw, funded by €180,000 of PLI's own income.
A €50,000 donation was also made to a mental health charity to ensure PLI didn't benefit from the draw.
The regulator found returns to good causes backed by the National Lottery were not harmed by PLI's actions.
The inquiry also found that player participation in the National Lottery's games was not negatively impacted.