Chancellor George Osborne will claim that 14m working households are £17 a month better off as a result of tax and benefit changes coming into force on Monday, as he battled to fend off Labour claims that he was planning to cut the top rate of tax to 40p in the next parliament.

In TV interviews on Sunday, Osborne four times ducked a challenge to rule out a cut in income tax for the rich in the next parliament, preferring to say he had no plans to cut the top rate of tax, the formula he used before the 2010 election, after which he then raised VAT. In separate interviews, David Cameron also refused to rule out a cut in the top rate of income tax.

The shadow chancellor, Ed Balls, branded Osborne’s evasion as another sign of the chancellor’s secret plan to make sure “millions pay more and millionaires pay less”.

But the Tories, determined to inject a feel-good factor into the election, will focus on the impact on incomes of more than 10 direct and indirect tax changes, coupled with welfare changes.

For months, opinion polls have shown an increase in the number of people expecting their economic circumstances to improve over the next 12 months, but this has not yet translated into a decisive shift towards the Tories in the polls.

At an Easter Monday rally,Cameron will say: “Today is a big day for our country. It’s ’money-back Monday’, a day when, quite simply, hardworking taxpayers get to keep more of their own cash. I don’t just want people to see Britain’s recovery on the TV or hear it on the radio, I want them to feel it in their lives.”

Drawing on an analysis prepared by Treasury civil servants and not Conservative researchers, the prime minister will claim the tax and benefit changes mean 22.5m households will be better off in 2015-16, including 94% of working households and 92% of pensioner households. Among all households, the average rise will be just £3.44 a week.

The 14m working households will be better off by an average of £17 a month, equivalent to £200 a year. A total of 6.9 million pensioner households will be £15 a month up: equivalent to £180 a year.

The analysis shows households in all parts of the income distribution will gain, with the top income decile benefiting the least and the fourth decile gaining the most. The median gross income of a two-adult household in the fourth decile is £23,300.

Cameron will claim there is a progressive and moral case for low taxes, and say: “It is wrong – frankly immoral – for government to spend money like it grows on trees. We know that there is no such thing as public money: there is only taxpayers’ money. And we know how we’d rather see it spent: not on bureaucracy or bloat or the latest crackpot government scheme, but on you, your family, your future.”

Insisting his tax priority in the next parliament is a further uplift in the personal tax allowance and taking more people out of the top rate of tax by raising the threshold, he will say the choice at the election is clearer than ever. “With the Conservatives, if you’re on minimum wage, no income tax. If you’re earning below £50,000, no higher rate of tax. With Ed Miliband, if you’re on minimum wage, [you’re] still paying tax, plus a £3,028 tax rise for every working family and nearly a million more paying the 40p rate.”

But in a speech in Leeds, Balls will highlight figures from the Institute for Fiscal Studies showing families are on average £1,100 a year worse off because of the government’s tax and benefit decisions stretching back to May 2010 – including the changes that come into effect on Monday. His aides say there is little point focusing on the coming year and ignoring the record of the parliament.

Balls will claim Osborne’s plans for deeper spending cuts in the next three years, set out in the budget, and £10bn of unfunded commitments, must mean another Tory VAT rise is inevitable, even though Osborne has ruled it out.

He will say: “The Tories have made £10bn of unfunded tax promises, which they have still not told us how they will pay for. That’s why people will conclude that to make their sums add up the Tories will end up putting our NHS at risk and raising VAT again.

“The Tories have broken their promises on VAT again and again and again. Because rather than asking those with the broadest shoulders to make a greater contribution, VAT has always been the Tory tax of choice.”

Balls will point out £10bn is the equivalent of a 2% rise in VAT. The Treasury’s own figures show this would mean a VAT tax rise of £360 a year for a couple with children, or £1,440 over four years.

The Liberal Democrats will join the debate about living standards, pointing out that Labour’s plans for a 10p starting rate in tax will only offer taxpayers a £37 tax cut, compared with the Lib Dem commitment to cut income tax by almost £400 in the next parliament through raising the personal tax allowance.