Fears among landlords and second home owners that tax would rise in budget said to be unfounded

The government is said to be concerned that putting up CGT would cost the Treasury money by slowing property sales. Photograph: Yui Mok/PA

Rachel Reeves will not change the rate of capital gains tax on the sale of second homes in the budget amid concerns about the impact on the property market.

Ministers have decided to leave CGT levied on the sale of second homes and buy-to-let properties untouched because of concerns that increasing it would cost money, the Times reported.

In the last budget, the Conservatives cut the top rate of CGT for property from 28% to -24%. The Office for Budget Responsibility said at the time the cut would raise nearly £700m by increasing the number of property sales and resulting income from stamp duty.

Now ministers are concerned that putting up the rate again would cost the Treasury money by slowing property sales, the Guardian understands.

Keir Starmer has indicated that CGT on the sale of shares and other assets, currently set at up to 20%, will increase in the budget on 30 October. The tax is expected to rise by several percentage points.

Only about 350,000 people a year pay the tax, but they contribute about £15bn in tax receipts, according to figures from the Institute for Fiscal Studies.

The Institute for Public Policy Research (IPPR) said that interviews it had carried out with millionaires suggested most would not be put off investing by a rise in CGT.

One, Julia Davies, told the IPPR she had “never let tax rates dictate my decisions to fund innovation or pursue opportunities”, while the Photobox co-founder Graham Hobson, said the claim that increasing CGT would discourage investment was “simply a myth”.

“Capital gains tax was equal to income tax when I set up Photobox. It didn’t stop me from starting and growing a successful business,” Hobson said.

The Treasury is considering changes to inheritance tax and pension tax relief. Reeves is drawing up plans for £40bn in tax rises and spend ing cuts to avoid the real-terms cuts to departments that had been baked in under the last government’s plans.

It emerged this week that several cabinet ministers have written to Starmer to contest planned cuts to their department.

The chancellor is also looking at increasing the national insurance contributions paid by businesses. The Guardian revealed this month that Reeves was considering levying NI on employers’ pension contributions, which thinktanks say could bring in £12-£17bn.

Increasing businesses’ NI contributions will be controversial and has provoked a backlash from industry groups, who have called it a tax on jobs, but Starmer and Reeves have refused to rule it out.

The prime minister told the BBC that Labour was “very clear in the manifesto that we wouldn’t be increasing tax on working people” but had made no commitments on employers’ NI contributions.

There is also growing speculation that Reeves will increase fuel duty for the first time since 2011, when it was frozen by George Osborne.

Bridget Phillipson, the education secretary, told the broadcasters on Thursday that the government had “some really tough choices” to make.