The game is played using twenty-six identical sealed green boxes, each with an identifying number from 1 to 26 displayed on the front. The boxes are opened by the contestants' family members. Inside each box is a label showing a different amount of prize money between 1 cent and €250,000. All the boxes are sealed by an independent adjudicator; the value inside each box is not known to Keith Barry, the contestants, The Banker or the production team before the game. To enter the game, players must purchase a Deal or No Deal scratchcard from a National Lottery agent, and reveal a "Deal" on the "Bankers Bonus" section of the scratchcard. Each week, players are selected to appear on the show from all scratch card entries received by the National Lottery, and the draw takes place live on TV3's Ireland AM.
The Deal or No Deal Scratchcard is largely based on the TV game show. Entry to the main game show on TV3 is only possible by purchasing the Deal or No Deal Scratchcard from any National Lottery agent. If a player reveals the word "Deal" on the "Banker's Bonus" section of the scratchcard, they can send it to the National Lottery in the special Deal or No Deal envelopes, for a chance to appear on the show. The Deal or No Deal Scratchcard costs €3.
The Irish version is virtually similar to the UK version. The values are the same as the UK version but in euros instead of pounds as well as additional amounts of 5c, €25, €2,000, and €150,000 to compensate for the fact that there are 26 boxes which are green rather than 22 red ones.