Burton indicates rich people will pay more in tax if she becomes Labour leader
The Social Protection Minister vowed to tackle tax breaks for high earners in what will prove controversial within Fine Gael circles.
While Ms Burton ruled out increasing the rates of tax, she said there are "certain exemptions" availed of by high earners that need to be examined.
"I don't think we need to increase the rates of taxation, but there are people in the Irish system, where there are some very attractive exemptions under certain conditions and that can result in people on very high incomes paying very little tax," she said.
She made the remarks after a candidate in the deputy leadership contest earlier called for a revised Programme for Government with a focus on taxation.
Ms Burton's call will be seen as the first shot in her battle to succeed Eamon Gilmore.
Junior Health Minister Alex White is tipped to also declare - but some party sources suggest his candidacy is by no means a certainty.