Mr Shearer said continuing contributions would not have increased net debt, but New Zealanders had seen it as borrowing to invest "and they didn't like that."
He said before the last election, Labour had not signalled its plans on the Super age well.
However, bold decisions were needed.
He said Labour had gone into the last election with policies that would have meant it had to borrow more in the short term, although the return to surplus would have been similar to National's programme.
"But we didn't win. New Zealanders told us they were uncomfortable about the rate of borrowing. We have listened."
He said until the country was back in surplus, any new spending would have to be paid out of existing money, through new revenue or re-prioritising. Limited borrowing would be allowed rather than selling state assets.