Reeves has suggested launching a £16 billion tax raid on pension contributions

LCP said it was more likely that the Chancellor would introduce a new, lower rate of employer National Insurance contributions, “starting relatively low but with the potential to generate additional revenue”.

It was found that there is a risk that such a policy will result in employers passing the costs on to employees in the form of less favorable salary waiver packages. Salary sacrifice is an agreement in which an employee agrees to give up part of his salary in exchange for non-monetary benefits, as this reduces the employer’s social security contribution.

However, the LCP said such a policy could be tempting for the Chancellor because it had the “potential to raise billions of pounds”, could be implemented quickly and would not reach voters’ wallets straight away.

Speculation is growing that Ms Reeves will focus on pensioners in her inaugural budget on October 30 in an attempt to plug a £22 billion black hole in the public finances.

One option available to the Chancellor would be to introduce a death tax on pensions. Balances accumulated in a pension fund on death are usually excluded from the estate for Inheritance Tax (IHT) purposes, while other assets such as an ISA are included. The report shows that the Chancellor may decide to withdraw this exemption.

Another possible source of revenue would be to reduce pensioners’ tax-free lump sum – the maximum amount they can withdraw from their pension pot tax-free. The left-wing think tank Fabian Society has recommended the lump sum be reduced from £268,275 to £100,000.

According to LCP, both options would increase “modest” amounts of additional tax revenue compared to the “political adversity” they would cause.