During the changeover from pound to euro, both currencies will be legal tender for 40 days. For almost six weeks, customers can use either Irish pound notes and coins, or euro notes and coins, or both in a single transaction. However, retailers will be expected to tender all change in euros and so will take a large responsibility for getting the new notes and coins into people's pockets. How will they cope?
Most large firms have been preparing for the changeover since the euro was introduced in non-cash form in January 1999. For instance, each of Dunnes Stores 86 shops in the Republic has its own euro co-ordinator and extra staff will be brought in during the changeover period.
However, there are fears that the dual currency period may not pass so smoothly for smaller retailers. Mr Pat Delaney, the Small Firms Association's chief executive, said many businesses had postponed euro training for staff because of the high mobility of the Irish workforce over the past year.
He said retailers would have much more cash on the premises than was usual, and this would have security implications.
"Small firms are going to have to carry a very significant burden at a time when they're very busy anyway because of the sales."
Mr Tony Farrell of the cash management company, Money Point, said many independent retailers still lacked basic equipment, such as dual currency tills, to facilitate the changeover.
"This leaves them vulnerable to a range of problems, such as accusations of price increasing and compounding customer confusion," he said.
Mr Peter Caviston, of Cavistons' fishmongers in Sandycove, Dublin, said he was particularly concerned about how his elderly customers would react to the changeover.
However, the project manager with the Forfβs EMU Business Awareness Campaign, Ms Yvonne Cullen, insisted there was no need for small business owners to panic even if they had not yet begun euro training for staff.
"The main message is: it's never too late. Obviously it's getting close but until you have to open your doors on January 1st you still have time to do something," she said.
Ms Cullen said the most important thing for every retailer was to know how they were going to handle the two currencies during the dual circulation period. As retailers were obliged to give change in euro, sales assistants have to store any pounds and pence tendered in a secure container until it could be exchanged.
Not all small retailers would need to buy new cash registers as many old systems could easily be upgraded. However, all retailers would have to modify or replace existing cash drawers as well as any coin trays or cash boxes when the seven Irish coins and five notes are replaced with eight euro coins and seven notes.
Ms Cullen estimated the pound would disappear quickly and the bulk of transactions would be in euro after the second week of the changeover.
Traders working through the night on December 31st - such as pubs and petrol stations - will be expected to finish their night's trading in Irish pounds - so people celebrating New Year's Eve will not be expected to grapple with the new currency at 12.01 a.m.
Ireland was the only member state to issue calculators to the retail sector and the EU has since recommended this as best practice for other countries.