Extending the pandemic bonus payment beyond core healthcare workers would be "incredibly difficult".
That's according to Public Expenditure Minister Michael McGrath, who was responding to criticism of the plan.
A once-off, tax-free €1,000 payment is to be made to frontline healthcare workers who were in COVID-19 exposed clinical settings.
While the Labour Party is calling for the bonus to be extended to low-paid private sector workers.
Its spokesperson for employment, Senator Marie Sherlock, says: "We believe we need to see a dividend for all essential workers.
"These workers are our cleaners, bus drivers, they worked round the clock in our shops, fire services, picked up our bins, and kept food on our tables.
"There are a range of mechanisms to identify these workers and reward them for their essential work, sacrifice and serve to our communities".
Minister McGrath told Newstalk Breakfast this wouldn't be easy.
"This is a really difficult issue - I think there's general recognition that the frontline healthcare workers went above and beyond.
"At the very beginning of the pandemic, in particular, they really didn't know what they were facing into.
"And they faced a level of risk that I think few others across society had to even countenance.
"And they did that and I think we owe them an enormous debt of gratitude.
"If you were to single out any one particular group, then I don't think many people would deny that that is the group that you should single out."
And he says the cost of the bonus would 'completely spiral'.
"That is not to say that there are not thousands of other workers across the country that went above and beyond... who worked really hard over the course of the pandemic to provide essential services to all of us.
"But if you seek to go beyond core healthcare provision, then it gets incredibly difficult to know where to draw the line - and the cost of this would completely spiral".
"I think we have to be reasonable, we have to be proportionate in our response".