The amount the government puts into KiwiSaver is reduced from today, Labour said, but the government disputes that.
Labour leader Phil Goff said the member tax credit paid by the Government into each KiwiSaver account to boost savings would be cut by 50 percent despite National's pledge that changes would not take effect until after the election.
"This broken promise undermines the KiwiSaver scheme by feeding many Kiwis' fears that the government can’t be trusted to keep its end of the bargain and flies in the face of constant messages that we need to save more as a nation."
Prime Minister John Key previously said that the changes would not kick in until after the election and a new government could reverse the changes.
"In July there is a new formula, but effectively what happens is that's not paid until an annual basis," he told reporters.
"So if there was change of government on November 26, and the incoming government decided they could afford to, and wanted to make a change, it could do so."