The Labor leader refused to fulfill Rishi Sunak's promise to spare the poorest pensioners from paying income tax.
It means that at least two million struggling elderly people will have to deal with this HMRC for the rest of their lives to pay taxes according to the simple tax system.
Chancellor Jeremy Hunt told the Daily Express: “Millions of pensioners will be worse off under Labour's Retirement Tax.
“For the first time in history, it will drag down retirees whose only income is income AOW to pay taxes for the first time.
“Not only does this make them poorer, but it also means the administrative burden associated with suddenly receiving a tax assessment.
“While sir Keir Starmer is on his personal gold-plated pension, with his own law, the pension tax on labor will hit retirees hard.”
Labor confirmed it will not match the Conservatives''triple lock plus,” including a tax break to avoid being dragged into paying income taxes.
A Tory source said: “Labour's pension tax will be administrative hell for ordinary pensioners.”
Silver Voices is launching its 'silver manifesto' general election campaign, calling on parties to ensure 'dignity in old age'.
Chief executive Dennis Reed said: “It is disappointing that Labour's initial response is to reject the proposal.
“It is a modest measure, we are careful with it. We would prefer it if lower-paid workers were included, but it is what it is and hundreds of thousands of retirees will potentially benefit from it.”
Baroness Altmann, the former pensions minister, said completing tax returns will be an “administrative nightmare”.
She said: “By opposing this measure, millions of pensioners will get more – many living on no more than the AOW– run the risk of having to fill out a tax form, which can be mind-bogglingly difficult, or failing to complete one and ultimately having to pay fines.
“We are already dealing with this issue for retirees who have shared part of their tax threshold with their partner through the marriage benefit.
“Their tax-free threshold is only £11,310, so completely new AOW is already higher and they will owe taxes.
“This will be an administrative nightmare and Labor will have to deal with it sooner or later.”
Tories warned that 10 million pensioners will pay extra taxes under the “employment pension tax”.
About two million elderly people, whose only income is income AOWare at risk of having to pay taxes for the first time.
Below the triple lock plus plan announced by the Conservativesretirees whose only income is the AOW will never pay income tax, because both the payment and the tax-free allowance for pensioners will increase in each year of the next Parliament in accordance with the highest income, wages or 2.5%.
It comes after two tax cuts for working-age adults in the last two financial statements, when National Insurance was cut by a total of four pence per pound.
Prime Minister Rishi Sunak explained the plans yesterday during a campaign visit to Staffordshire.
He said: “You can just look at what the last Labor Prime Minister did for pensioners and that was Gordon Brown.
“I think every pensioner remembers the 75p increase in the pension scheme AOW and Gordon Brown's £100 billion tax attack on pensions.
“Today it is clear that in these elections there is only one party that is on the side of the pensioners. There is only one party that offers a tax cut for pensioners.
We are – and we also protect the triple lock which is currently rising by £900.
“Labour have said they don't support our policy of raising the threshold and going back to what we had before, which is a pensioner's allowance that will give them a tax cut.
“Labor is against that. This means that under a future Labor government, pensioners will go to work AOW will start paying taxes.
“But that is the reality. So a clear dividing line. Retirees can remember what Gordon Brown did and what they heard about today Keir Starmer and Rachel Reeves that they will be taxed under a future labor government.
So it's a pretty clear choice in these elections.
“I would provide a secure future for retirees because I believe that if you work hard and commit all your life, you earn dignity when you retire.
“And that's the kind of country I believe in. That's the kind of country I think most people believe in and current policies reflect that.”
Shadow Chancellor Rachel Reeves defended Labour's refusal to match the deal triple lock plus promise.
She told Sky News: “I want to see taxes lower for working people and pensioners, but to do that you have to explain where the money is going to come from. And yesterday the Conservatives used this pot of money to create a national agency. Today they say they are going to use this money to cut taxes. The truth is that the Tory sums are simply wrong.”