Last March, the political system sat bolt upright when it saw estimates for how much Ireland could owe for missing targets to cut carbon emissions.
The fallout might be colossal at between €8 billion and €26 billion.
The higher figure is more than Ireland spends on healthcare in one year.
The estimates were calculated by the Irish Fiscal Advisory Council and Climate Changes Advisory Council.
The costs would be incurred because Ireland is part of the EU's legally binding mechanism to reduce emissions.
It encourages member states to cut pollution by imposing costs if they miss targets.
The EU Effort Sharing Regulation covers areas of agriculture, transport, buildings, waste and small industries.
Senior officials in Government have worried for some time that Ireland could face an enormous cost and were keen for the Irish Fiscal Advisory Council to analyse the potential liability.
The system works like this: every country is expected to cut its emissions by 2030, with member states which exceed their target getting a credit.
While those that do not, like Ireland, must buy credits.
Countries that pollute more are penalised and the EU member states that exceed their targets benefit financially.
Ireland is required to reduce emissions by 42% compared to 2005 levels, but it will not meet that goal.
It has the largest emissions per person in the EU for the sectors covered by the regulation.
Since the cost estimates were published, a quiet lobbying campaign by the Government has been under way in Brussels to try to secure concessions.
Ireland is not alone.
Some big countries will not meet their targets either.
That is likely to make credits more expensive to buy and is the basis for the calculation by the Fiscal Council and the Climate Change Advisory Council.
Minister for Climate, Energy and Environment Darragh O’Brien said there is not yet an agreed formula for the cost of compliance.
"That type of cost mentioned publicly, that is not a realistic cost," he said.
He has been in negotiations with the Danish presidency of the EU and with Commissioner for Climate Wopke Hoekstra.
Read more: Latest Climate Change stories
Taoiseach Micheál Martin will also discuss the issue with European Commission President Ursula von der Leyen.
Mr O’Brien said Ireland’s preference is to put money into "decarbonisation and electrification".
He wants recognition from the commission for investments such as the €3.5 billion going into national grid improvements to offset carbon emissions costs.
He said discussions with the EU need to include "recognising the unique nature of Ireland’s agricultural sector" in comparison with other European countries.
Farming is the crux of the issue.
Among sectors covered by the Effort Sharing Regulation, agriculture is responsible for 51% of Ireland’s emissions, transport produces 26% and homes account for 13%, according to the Environmental Protection Agency.
The Government’s argument is that Ireland’s population is growing, unlike many other EU countries, and that has a role in increasing emissions.
It said investment in public transport has increased while residential and commercial buildings are now built to higher standards.
Under the EU system, wealthier countries are expected to pay more.
Ireland is awash with money from multinationals, which massively inflates the size of the economy as measured by Gross Domestic Product figures.
Oisín Coughlan, policy adviser with the Environmental Pillar, said: "I don’t see there being huge sympathy for Ireland.
He said: "Ireland has had the Apple money and lots of tax money generally.
"It’s not short of cash.
"I would rather Darragh O’Brien devote his energies to reducing emissions rather than ask the EU to let us off the hook."
Brian Motherway, International Energy Agency’s Head of Energy Efficiency, said: "It is fair concern for Ireland to point out its unique situation.
"But every country has a unique situation."
Mr Motherway said agriculture "is a particular challenge for Ireland", adding that "in other parts of Europe, they have heavy industry that we don’t have, like iron and steel".
He said: "They are all facing decisions.
"If it is more difficult or less palatable to reduce emissions in agriculture, then the focus needs to be put elsewhere.
"Ireland spends billions every year importing fossil fuels which are polluting and which are expensive."
Director of the National Economic and Social Council Larry O'Connell said the "big issue with agriculture is the herd size – are you going to reduce it or not?"
Mr O’Connell added: "What does the future look like? What are the options for farmers? What are the alternative activities they will be involved in?"
The EU member states may not reach consensus on granting concessions to countries such as Ireland - a number of them are likely to benefit from selling credits.
In such a scenario, Ireland may find it difficult to secure concessions.
Despite Mr O’Brien’s assertion that the costs of emissions have yet to be agreed, the Irish Fiscal Advisory Council and the Climate Change Advisory Council stand over their figures.
They say their analysis was "thorough, robust, and independently peer-reviewed", adding it "examined a range of potential outcomes in the event that Ireland does not comply with its legal obligations".
They make the point that Ireland has paid costs in the past when it missed emissions targets, as it did under the Kyoto Protocol.
And Ireland has also foregone revenues of €100 million per year under the separate mechanism covering sectors of aviation, energy and heavy industries.
In other words, regardless of lobbying, when Ireland misses its targets on agriculture, transport and buildings there is likely to be a cost.
And it will be large.
