Working people won’t see higher taxes “on their payslip”, a minister said as she acknowledged frustrations over the government’s refusal to spell out who will be hit with higher charges ahead of the Budget.

Education Secretary Bridget Phillipson repeated warnings that Wednesday’s accounts will include “tough choices”, but she insisted it is a choice between investment or decline for the UK.

However, the government minister refused to say whether a small business owner earning £13,000 a year is considered a “working person” who should be protected from tax rises in Rachel Reeves’ first budget.

Before Sunday morning broadcasters, Phillipson was repeatedly pressed to define the Labor government’s use of the term “working people” – which it has promised to spare from “key” tax increases.

“You’re inviting me to speculate about the kind of question you’re asking,” she told the BBC’s Sunday With Laura Kuenssberg programme.

“What I’m saying is, when people look at their paychecks, they’re not going to see higher taxes.”

Speculation has grown that people who make money from assets such as property could face higher fees in the Budget after Sir Keir Starmer suggested they do not fall within his definition of “working people”.

Labor had committed in its manifesto not to raise taxes on working people, which expressly excludes increases in VAT, National Insurance and Income Tax.

But the chancellor is expected to raise employers’ – rather than employees’ – social security contributions by at least one percentage point in the budget, which could hit small businesses particularly hard.

Asked whether a small business owner making a net profit of around £13,000 would be considered a working person, Phillipson said: “We can go through a range of hypotheticals about who might or might not be caught by tax measures that might or might not happen in the budget.

“When Rachel sits here next weekend you can ask her about the measures she has announced.

“I know it’s frustrating on the budget that I can talk about some areas, but not everything. I appreciate your frustration.

“I would love to come and say ‘here are all the measures line by line’, but that’s not my job – that’s for the chancellor.”

Ministers have also refused to rule out the freezing of income tax thresholds introduced by the previous government, which sees people drawn into paying higher rates due to a phenomenon known as “fiscal drag”.

Reeves described such freezes last year as “picking the pockets of working people” as the Conservatives pressed ahead with the policy, prompting Tory accusations of hypocrisy over Labour’s own expected extension of it.

Challenged on his claim that working people will not face a greater burden “on their payslip” in light of the prospect of the thresholds remaining frozen, Phillipson told Times Radio: “I’m just not prepared to speculate on hypotheticals.”

Further confusion was sparked on Sunday after it was reported the Chancellor would not announce any new free ports in the Budget despite a Number 10 press release on Friday saying five more would be revealed.

The Financial Times quoted a government official as saying the announcement had been a “total cock-up with communications” and that Reeves will instead reveal the “next steps” for five of the existing tax-free zones.

These freeports will be given official permission to have custom sites within their borders while plans for a separate “investment zone” in the East Midlands, first put forward by the Tories, will also be approved, the newspaper reported.

Downing Street and the Treasury did not immediately respond to requests for comment.

Although ministers remain tight-lipped, several other measures are expected in Wednesday’s statement, including a lowering of the income threshold at which employers pay their social security contributions.

Combined with a rise in employer contributions, this is expected to raise around £20 billion as Reeves tries to revive public services and put the economy on a firmer footing.

Some £1.4bn has already been announced to rebuild crumbling schools, as well as a tripling of investment in free breakfast clubs, £1.8bn to expand state-funded childcare and £44m to support kinship and foster carers.

Speaking on Sunday, the Education Secretary said she “loves to move faster” to strengthen protections for vulnerable children, but that it will “take time”.

“We have seen the steady erosion of support services for families,” she said.

“But it’s going to take us time, and I’d love to go faster on some of this – I absolutely would. But there’s a lot we can do right now.”

The Cabinet minister also declined to guarantee that nurseries would be protected against increases in employers’ national insurance, saying only that she was committed to improving early years.

“They can be confident that I am working with them to deliver a brilliant early years childcare system,” she said.

Reeves is also expected to target public sector net financial debt (PSNFL) as his new measure of debt rather than the current measure of underlying public sector net debt.

A move to the PSNFL would give her more room to meet her debt-reduction goal, as it includes a broader mix of state assets and liabilities — notably including expected student loan repayments to offset some of the debt.

Capital gains tax, inheritance tax and fuel tax are some of the other levers Ms Reeves could potentially pull to boost revenue as she tries to put the economy on a firmer footing.

In an interview with the Observer, she suggested she wants Wednesday to match the biggest moments in Labour’s economic history.

She said: “In 1945 we were rebuilding after the war; In 1964 we rebuilt with the “white heat of technology”; and in 1997 we rebuilt our public services. We have to do all that now.”

Meanwhile, in an article for The Sun On Sunday, she said the statement would be a “budget for the aspiring”.

Shadow science secretary Andrew Griffith said Labor was “essentially lying to the British people” about its plans, and he compared the party’s behavior to the “worst form of dodgy car hire companies”.

“Already after 110 days, I think people see that this government came in on a false prospect that things would be easy,” he said.

“They are essentially lying to the British people about their plans not to raise National Insurance … not to change the tax rules.”

Paul Johnson, director of the Institute for Fiscal Studies, warned that some public services may continue to feel under pressure despite “one of the biggest tax-raising budgets ever”.

He told Sky News: “Justice, local authorities, social care, police, prisons, they’re all really struggling at the moment.

“So again we’re in this really tough situation where we can have the biggest tax increase budget, or one of the biggest tax increase budgets, ever and yet a lot of public services are still feeling the squeeze.”

Former Bank of England governor Mervyn King warned that higher borrowing would also hit long-term interest rates, which would “bear the brunt”.

Lord King added: “Certainly if you borrow more, it doesn’t matter how you dress it up in terms of a different fiscal policy rule, people know that higher borrowing means higher borrowing, and the financial markets and people lending to the government will require a somewhat higher interest rate to compensate for the higher amount of debt they are asked to finance.”