Swim Ireland says it will take action after Sycerika McMahon missed out on competing in the breaststroke at the World Championships in Barcelona.
McMahon was unaware she didn't have the A standard needed for the event within the specified time period.
She claimed that no-one from Swim Ireland pointed this out to her until after the time window had elapsed.
Swim Ireland plan to ensure that every swimmer and their coach are made aware of time periods for qualification.
The 18-year-old from Portaferry made the breaststroke A standard for the World Championships in securing a silver medal at the European Championships in May 2012.
McMahon believed this qualified her for the breaststroke in Barcelona.
However, the qualification period did not start until 1 July last year and McMahon's best was a B standard time in February.
As another Irish swimmer, Fiona Doyle, had the A standard, McMahon couldn't be entered in breaststroke events with a B time.
While training in Italy earlier this month she received a phone call telling her she did not have the required time during the qualifying period - the first time Swim Ireland had informed her.
"I want to make sure next time that every athlete and coach is very aware of any intracacies of the rules that they may not be aware of," said Peter Banks, Swim Ireland High Performance Director.
"Last year when we brought everyone together at the start of Olympic year we made everbody aware of those particular regulations.
"We didn't restate it this year so maybe we have to re-do it every single year."
McMahon is also concerned that her funding will be reduced as a result of not competing in the breaststroke in Barcelona.