Five thousand people have been ordered to pay more property tax after they had undervalued their home.
Around 10% of those had €200,000 added to the value of their home by Revenue.
The compliance rate this year is 94%. Four hundred people who refused to pay have been referred to the sheriff.
Revenue’s local property tax project manager Vivienne Dempsey said they were taking action against people who had not paid.
"Several hundred cases have already been placed in the hands of the sheriff since September," she said.
"For PAYE cases, we have imposed a mandatory deduction at source. For self-employed cases, we have a range of sanctions including refusing a tax-clearance cert, imposing a surcharge and now moving to collection and placing the liability in the hands of the sheriff."
Revenue’s Collector General Michael Gladney said they were now investigating the 6% of people who did not comply this year, to find out why.
"We're starting to work down through the properties that didn’t comply," he said. "In certain incidents we're finding non-compliance and we're dealing with that.
"(In others), we're finding issues in the case where perhaps our registry information was not quite correct, where it was a commercial property rather than domestic property (for example)."