A dozen tax inspectors will be among the revellers at this weekend's Prince concert.
Revenue confirmed officers will be quizzing stall operators and their employees about their taxes while up to 30,000 music fans enjoy the gig at Malahide Castle in north Dublin.
Revenue is targeting cash businesses as part of a probe into Ireland's multimillion-euro black economy during the recession.
Similar checks have been carried out by officials at Slane, Oxegen, Electric Picnic and major sporting events.
A Revenue spokeswoman said its focus is on any sector that has the ability to deal in cash.
"In our experience, one of the biggest risks is the suppression of sales and under-declaration of income and profits," he said.
The Malahide Castle show is the only stand-alone concert Prince will play in his European tour, with the rest of the appearances at festivals.
Concert organisers have said the pop legend is on a mission to prove a point to his fans after cancelling his Croke Park date three years ago at short notice.
His controversial no-show in June 2008 cost him 2.2 million euro.
Gates open at 4pm on Saturday, with Chicago nine-piece Hypnotic Brass Ensemble taking to the stage at 5.45pm. Prince will start his set at 8pm.