Nick Clegg will say later that he wants the coalition government to go "further and faster" in raising the pay level at which people start paying income tax to £10,000 a year.The deputy prime minister will argue that many families are at financial "boiling point" and need more relief.
The coalition has promised to raise the income tax threshold to £10,000 by the next election, set for 2015.
Labour said Mr Clegg had "a cheek preaching about fairness and tax".
The deputy PM's speech to the Resolution Foundation in London follows official figures showing the economy shrank by 0.2% in the final quarter of 2011.
It also comes ahead of the Budget on 21 March, increasing speculation that changes to tax thresholds could be announced.