Theresa May has insisted Tory tax plans have not changed after a senior cabinet minister signalled there would be no income tax increase for higher earners.
The prime minister said it was her party’s “firm intention to reduce taxes on ordinary working families”.
But Sir Michael Fallon said in the Daily Telegraph that there would be no rise in income tax for higher earners.
Labour leader Jeremy Corbyn said the Conservatives’ tax policies were in “chaos”.
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The Conservative manifesto scrapped a pledge made by David Cameron in 2015 not to raise VAT, national insurance or income tax.
“What people will know when they go to vote on Thursday is that it is the Conservative party that always has been and is and always will be a low tax party and it is our firm intention to reduce taxes for ordinary working families.”
However, in his Telegraph interview, Sir Michael appeared to go further than Mrs May.
He said voting Conservative was “the only way” people could be sure income tax would not be hiked.
Asked if high earners could confidently vote Conservative next week, safe in the knowledge that their income tax would not go up, Sir Michael said: “Yes.
“You’ve seen our record. We’re not in the business of punishing people for getting on, on the contrary we want people to keep more of their earnings.
“The only way they can be sure their taxes won’t rise is to vote Conservative. We already know your tax will go up if you vote Labour on Thursday.”
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The Conservative manifesto had committed the party to keeping tax “as low as possible” but had not ruled out increases in income tax.
‘No shopping list’
Foreign Secretary Boris Johnson later told BBC’s Newsnight: “We will bear down on taxation and we have absolutely no plans to raise income tax. Our plans are to cut taxes. Labour’s plans are to put them up.”
Former Conservative work and pensions secretary Iain Duncan Smith told BBC Breakfast the party was trying to get away from the “idea that you set out every single thing in detail saying we won’t do this, we won’t do that, we won’t do the other because then you get a large shopping list”.
At the 2015 general election, David Cameron promised that income tax, National Insurance, and VAT – the so-called “triple lock” – would not go up under a Conservative government.
That promise lead to a U-turn earlier this year when Mrs May’s government had to ditch plans to raise National Insurance contributions for the self-employed.
The Tories have pledged not to raise VAT but to increase the personal allowance to £12,500 and raise the minimum earnings for the 40p higher rate to £50,000 by 2020.
Analysis by BBC political correspondent Leila Nathoo
Sir Michael Fallon’s comments were a signal to the Tory base – designed to reassure core supporters that their taxes wouldn’t go up under the Conservatives and make sure they turn out to vote.
There is no firm commitment though, no promise in writing unlike in the party’s previous manifesto.
And Theresa May didn’t go as far as her defence secretary, declining to make a new pledge – suggesting this isn’t something she wants to be held to.
Labour have seized on the discrepancy as a sign of Conservative confusion – with Jeremy Corbyn reminding voters of his claim that 95% would pay no more tax if he won power.
All parties are fighting hard in these last few remaining days of campaigning to make sure their key messages get through.
Opposition parties seized on Sir Michael’s comments.
“One minister says they’re going to give no more tax rises – indeed possibly tax reductions for the very wealthiest – then they can’t answer the question about tax rises for the rest of the population,” Mr Corbyn said.
“Let’s be clear – what Labour are offering is no tax rises or national insurance rises or VAT rises for 95% of the population.”
Former Lib Dem business secretary Sir Vince Cable asked where the money was coming from to pay for Sir Michael’s apparent promise.
“Since they are ruling out increases in income, corporate tax and VAT we must assume that there will be an increase in national insurance and in various ‘stealth taxes’ yet to be specified. It undoubtedly raises suspicions,” he said.
The SNP’s Stewart Hosie said Sir Michael had “let the cat out of the bag”, adding: “Tory plans for a tax freeze for the richest in society were clearly airbrushed out of their manifesto.”
What are the other parties pledging?
Labour has promised to raise the income tax rate to 45p for earnings above £80,000 and to 50p for each pound earned over £123,000.
It says it will not raise income tax for those earning less than £80,000.
It says the planned rises for higher earners will help fund billions of pounds of investment for schools and the NHS and an expansion of free childcare, in what it calls a “programme of hope”.
Meanwhile the Liberal Democrats have pledged to increase income tax by a penny to help pay for the NHS, social care and mental health.
The SNP says it would support the idea of raising the top rate of income tax for those earning more than £150,000 from 45p to 50p.
It says there would be no increase in taxation on the low paid, in national insurance or in VAT.
Whereas, the Green Party wants to implement a wealth tax on the top 1% of earners and introduce a “Robin Hood” tax on financial transactions.