Tipping by cash is still the best way to help ensure staff actually get to keep the money, the UNITE union says.
Julia Marciniak, hospitality and tourism coordinator from UNITE, says the odds of a tip ending up in a server's pocket can actually be "shockingly low".
It comes as the Government works on legislation that would legally protect workers' tips.
Under the proposals, tips will not be counted towards an employee’s basic pay and will instead be considered "additional and separate".
Employers will also need to "display prominently" their policy on how cash and card tips are distributed.
The new law will also cover service charges, although the Government says such charges will not be considered "outside the scope of a person’s contractual wages".
For now, however, Ms Marciniak told The Pat Kenny Show leaving a tip is no guarantee a server will get their fair share.
She said: “From my own personal experience, in only two out of 12 places I was employed I got all my tips.”
She said a recent survey carried out by her union showed only 40% of staff received cash tips left by customers, but that dropped significantly when it came to credit card tips and service charges.
As a result, she said cash is “still the best way to tip” - as that has the highest chance of workers keeping the money.
Still, Ms Marciniak said work is still needed to ensure staff get their fair share - and she believes workers should decide a business' tipping distribution policy.
She said: "Sometimes workers receive about 10% of the cash tips they created, because the managers are in charge of counting the tips and sharing the tips.
“There’s absolutely no clarity for the workers, and it’s even worse if the tips are shared weekly or monthly.
“It doesn’t need to go to individuals - the workers should be in charge of the policy in place with sharing tips.
“We know chefs are slightly better paid than front-of-the-house. [Servers] are more likely on the minimum wage."
Adrian Cummins, CEO of the Restaurants Association, said his organisation welcomes the decision by Government to bring forward legislation around tipping.
He said: “To be very clear here… I think the vast majority of employers are doing the right thing.
“As seen in the Irish Independent this morning, the vast majority of restaurants that have been asked do pass on the entire tip to [staff].
“What we believe is very much a transparent approach to this.”
Mr Cummins said many restaurants do have an internal staff policy, decided by staff themselves, to ensure all workers gets a share of tips - including back-of-house and kitchen staff.
He also said his own organisation previously directed employers to put up signs to tell customers that all tips went to staff.
He also suggested workers should go to the WRC if they have an issue about not being paid properly.