Alistair Darling is to set out how he plans to answer Labour MPs' concerns over the abolition of the 10p tax rate.
Pensioners and young people who have lost money as a result of the abolition of the 10p tax rate are to be given compensation, Alistair Darling says.
The chancellor is to issue a written statement - as the number of Labour rebels who have signed a motion criticising the measure rises to 46.
In what will be seen as effectively a U-turn, the chancellor said he would assess the average loss to pensioners aged 60-64 and childless people.
A source said Mr Darling hoped to "flesh out the process" of how he plans to help those affected by the change.
He will then announce what the Treasury will do to compensate those affected, with the money backdated to April.
It comes as the ranks of Labour rebels concerned by the measure rose to 46.
Gordon Brown is likely to be pressed on the issue in the House of Commons in Prime Minister's questions from noon.
Gordon Brown is likely to be pressed on the issue in the House of Commons in Prime Minister's questions from noon.
Both he and Mr Darling have held a number of meetings to spell out their case in a bid to win over potential rebels, with the chancellor promising to address concerns "within this financial year".
His official spokesman said: "There is no question of not going ahead with the abolition of the 10p tax rate. It was the right thing to do."
'More details'
Commenting on his pending statement, a government source said: "He is going to flesh out what he said on Sunday and what he said to MPs yesterday.
"He's said he was going to revisit it in the pre-Budget report and the Budget, but some people want more details.
"He has had a very serious discussion with MPs and he's accepted the argument that they want more details."
EFFECTS OF TAX CHANGES Winners: Most people with incomes of £17,500+Under £17,500 but aged 65+ and therefore eligible for higher personal allowancesUnder £17,500 but with young children and therefore eligible for child tax credits Losers: Under £17,500 and ineligible for working tax credits because under 25Retired early and therefore ineligible for higher personal allowancesPart-timer working insufficient hours to qualify for tax credits Different personal circumstances may affect final amountsSource: PWC Tax changes explainedAnalysis: Darling's options
The source added that Mr Darling would give "some indication of how he is going to approach it and some indication of timing, and flesh out the process."
It comes as an amendment, tabled by ex-minister Frank Field and calling for compensation for those hit by the ending of the 10p rate, was signed by 46 Labour MPs - up by seven overnight.
If all 46 Labour rebels and opposition parties backed Mr Field in a vote the government would be defeated.
Mr Field wants £1.2bn in unclaimed working tax credits to be used to help people hit by the end of the 10p rate.
The former welfare reform minister, told The Guardian: "We need to send a clear message to low-income voters that they are going to be recompensed this year for the increased taxes they paid."
Mr Field said his amendment was not intended to destabilise the government.
"I feel sick when I vote against the government, but I think it is very important that the low paid know we are going to deliver."
At a meeting on Tuesday, Mr Darling promised Labour MPs that action to compensate low-income households would take effect within this financial year.
While I have signed Frank Field's amendment, I am very hopeful it won't be needed after last night's excellent meeting Ann CryerLabour MP
Some MPs said they thought Mr Darling might consider backdating compensation for low earners who have lost money.
Meanwhile, the Commons Treasury Committee is to hold a short inquiry into the effect of axing the 10p income tax rate.
The cross-party committee, chaired by Labour MP John McFall, intends to complete its probe, including recommendations for action, before the Bill completes its final passage through the Commons, probably no earlier than June.
Downing Street said on Tuesday the government was "working hard during the course of the next week to persuade MPs of the merits of its case".
The decision to axe the 10p rate was taken in Mr Brown's final Budget as chancellor last year and came into effect this month.
Lib Dem leader Nick Clegg told the BBC the abolition of the 10p rate had caused "absolute uproar amongst the poorest, most vulnerable families, who are feeling overstretched already".
Conservative leader David Cameron has pledged to "stop the government in its tracks" and make them "think again" over abolishing the 10p rate.
The changes, which came into force this month, abolished the 10% starter rate of income tax, but lowered the basic rate from 22% to 20%.
The Treasury committee has said single people with no children earning under £18,500 will lose up to £232 a year as a result of the changes.
Ministers say rises in child benefits, state pensions and tax credits have gone up, benefiting millions of people.
