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
Michel Platini has formally announced that he intends to stand for the Fifa presidency when Sepp Blatter vacates the position
Microsoft's new system Windows 10 has been met with approval after its disastrous predecessor but users have yet to be entirely convinced.
Alton Towers crash victim Leah Washington, who lost a leg as a result of the horrific incident, celebrated her 18th birthday last night.