The Liberal Democrats want the coalition to raise the income tax threshold above £10,500 by 2015, which could effectively mean a £100-a-year tax cut to 24 million basic rate payers.
The move, which would take half a million people out of income tax altogether, would represent a £1 billion tax giveaway before the next general election.
The Lib Dems have already seen the coalition achieve their manifesto commitment to raise the personal allowance to £10,000 - which was finally reached in the last Budget in March.
Lib Dem leader Nick Clegg will write to party activists next week calling for a "workers' bonus" to reward voters for the financial sacrifices they have made during the years of austerity.
More top news
A documentary about the brutal gang rape and murder of a woman on a Delhi bus in 2012 has been banned in India.
Scotland Yard are asking for the public's help to find the dangerous men who are wanted in Europe but are believed to be hiding in the UK.
A Bolton chemistry teacher is to be sentenced today after admitting terror offences - with police claiming he wanted to join Islamic State.