Leftover punts and other Irish coins and notes that miss tonight's spend-by deadline will be exchanged by the Central Bank indefinitely, the bank said yesterday.
Commercial banks have also agreed to accept old money for an unspecified time, but are likely to call a halt to the practice within a few months.
The Central Bank, however, expects to be seeing the coins for some time to come.
"We will be continuing to accept them for many years. We are still getting in some old Lady Laverys," said Mr Hugh O'Donnell of the Central Bank press office.
"Things surface when elderly people die or when old houses are being knocked down or when a field is opened up for the first time in 30 years.
"Tomorrow is only the end of legal tender - the currency will still exist."
Anyone handing in old money to their local bank in the coming weeks or to the Central Bank in Dame Street, Dublin, after that will receive the equivalent in euro at current exchange rates.
"We were trying to get the commercial banks to agree to a common finish date, but different banks have different types of customers and they feel they want to respond to their particular customers' demands," Mr O'Donnell explained.
Charities can also continue to benefit from the old notes and coins after midnight tonight.
However, sorting the old coins from the new may place an added burden on volunteers working in smaller organisations.
The Pennies from Heaven campaign, which represents 11 national charities working in the fields of healthcare, childcare and homelessness, has extended its collection to March 5th.
By that time the organisers expect most donors will be out of old money.
"We are already getting euros in collection buckets," said a spokeswoman, Ms Mags McLoughlin.
The 3,000 collection points around the State had also turned up a whole range of European coins as well as US dollars, Indian rupees, old eastern European money and other rarities.
"We're not refusing any of them," she said.
"We have a good deal with an exchange company and we can turn every type into money the charities can use."