The Department of Social, Community and Family Affairs has begun payment of arrears to an estimated 5,000 pensioners who lost out by making late claims.
Almost £600,000 has been paid in time for Christmas to some 300 applicants, but the Department estimates the final bill will come to £10 million.
Individual payments range from £30 to £9,000, with an average of £2,000.
The arrears are being paid to those on contributory old-age pension, retirement pension, and widow's/widower's contributory pension.
The Department is inviting claimants who believe themselves owed money to apply now for back-payment, even if they have been refused previously.
The payments arise because of what a spokeswoman said were improvements in the arrangements for backdating claims. These had first applied only to claims made since the start of 1997, but have now been extended to claims made earlier. Only a proportion of the total arrears due will be paid, however, depending on the circumstances of each case.
Pensions staff are to carry out a computerised trawl early in the new year to identify claimants who are still owed money. The Department may then take out advertisements inviting applications for back-payment.
The Minister for Social, Community and Family Affairs, Mr Ahern, said the payments highlighted the Government's commitment to improving the position of the elderly, "particularly since 1999 has been designated UN Year of Older People".
