All Irish-born people reaching 100 years will be eligible for the €2,500 bounty, irrespective of where they live, Taoiseach Bertie Ahern announced.
He said that up to now the bounty was payable only to centenarians living in the State, regardless of nationality.
"Over the past decades, hundreds of thousands of our people emigrated out of economic necessity," he added.
"They made a huge contribution, not only to their adopted country but many of them continued to contribute to their family in Ireland by sending home remittances.
"The centenarians' bounty is not just a practical gesture; it is also a token of regard."
Mr Ahern said that at a time in life for older emigrants, when friends and family in Ireland might no longer be as numerous as they once were, it was a fitting gesture that the State should acknowledge their 100th birthday.
He added that there was provision in the scheme, whereby someone born before 1906 who did not apply previously, could do so retrospectively.
Replying to a series of questions, the Taoiseach said that some time ago, when he debated the issue with the Federation of Irish Societies, he had commissioned a statistical exercise to determine the figures for people born in 1904. "In that year, 103,811 people were born in the 32 counties. An actuary calculated that 625 should be alive on their 100th birthday."
When Labour leader Pat Rabbitte suggested that there were probably many more than that on the electoral register, Mr Ahern replied: "God knows. Only 141 bounties, however, were paid in 2005. Whatever the figure, on that basis we lost close to 450 or 460 of the centenarians.
"There are Irish people who did not receive the bounty, so it is worth making an effort to find them. This corrects a matter that elderly people considered unreasonable."
He said that working on 1904 figures, and at 141 bounties under existing arrangements, the gross cost was €352,000. "Based on actuarial figures, there should be about 480 other centenarians living outside the State.
"Considering the number living in the State, this figure seems high, but even if it is correct, the cost would be €1.2 million."
Mr Rabbitte said that few of the people whose interests his party had sought to advocate would survive to 100 years.
"Many of them are in bad circumstances in British cities, living in very poor conditions and so on and, unfortunately, will not experience a life of 100 years or more."
