Ireland's population could grow much faster than previously expected, according to new scenarios published by the Department of Finance.
In a high growth scenario there would be 7.59 million inhabitants by 2065, up from the current level of 5.45 million.
The estimate is significantly above most recent projections from the Central Statistics Office (CSO).
John McCarthy, the Chief Economist of the Department of Finance, said the department’s estimate was higher due to larger forecasts for immigration.
In a central growth scenario, the population would reach 6.7m by 2065 and in a low growth estimate it would be 6m.
The department produced the estimates to ensure the Government is prepared for Ireland’s changing demographics.
Mr McCarthy said: "One of the reasons we are where we are with housing is the population."
An increasing old-age dependency ratio would put pressure on the public finances, with rising costs for pensions, healthcare and social services.
While there will be more immigration, the proportion of children born to women in Ireland is expected to continue to decline.
The fertility rate has fallen from close to 2.6 births per woman 40 years ago to 1.53 births today.
That rate is expected to fall to 1.3 births per woman by 2038 before stabilising.
The growth in the population is expected to be driven by immigration.
A high growth scenario for net migration, or people arriving minus those leaving, is expected to see up to 58,000 additional people coming to the country per year over the coming decades.
The central estimate is up to 40,000 and the low scenario is 18,500.
In its report, the Department of Finance said: "If net migration was to fall to zero by 2035, Ireland’s labour force would contract from that point onwards, while the number of people ageing out of the labour force would continue to grow."
It adds: "The economic consequences of such a fall would potentially be very negative - posing major challenges for Ireland’s enterprise base, diminishing the capacity of the State to provide public services, and ultimately reducing living standards as a shrinking labour market constrains economic growth."
The analysis also highlights an issue as half of migrants with critical skills work permits are leaving the country within five years to work elsewhere.
