More than 2,000 people have admitted to under-declaring the value of their homes in property tax returns since November.
Homeowners who haven't been truthful with the taxman now have until the end of March to come clean.
Revenue said last week that it had collected almost €1.5m a day after it threatened to haul homeowners before the courts for not paying up before the end of the month.
The surge in payments follows Revenue's warning that it would impose tough penalties.
A Revenue spokeswoman said 2,100 people have increased their property valuations since November.
"They self-corrected themselves. What you do is you go online and revise the valuation – and make arrangements to pay the difference," the spokeswoman said.
"If you valued your property honestly, using the information available to you as of 1 May, 2013, you have no reason to increase your valuation."
