The deal is particularly significant for the board as together the 12 PCAOB-registered firms in Ireland currently audit companies listed on the US stock exchanges with a combined market capitalisation of about $75bn (£57.4bn).
“Ireland is a very important jurisdiction for global investors, especially as more multinational companies set up operations there,” said PCAOB director of international affairs Bruce Wilson.
IAASA is the fifteenth national regulator in Europe to reach a cooperative agreement with the board. Others are from the UK, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Luxembourg, the Netherlands, Norway, Spain, Sweden and Switzerland.
Under the US Sarbanes-Oxley Act, the PCAOB oversees and inspects all firms that audit public companies whose securities are traded in US markets.
According to the watchdog's statistics, almost 900 audit firms on its current register are located in 84 countries outside the US.
PCAOB chairman James Doty said that the deal reflected the two organisations’ common interest in enhancing investor protection in their respective markets through rigorous audit oversight.