In a parliamentary session at Holyrood, finance secretary Derek Mackay was asked to set out the government’s position regarding a possible increase in the current 45p rate for those earning over £150,000. 

Under devolved powers, the Scottish government has the ability to vary rates of income tax by up to 10p. Previous discussions have centred on concerns that introducing a 50p rate could see high earners either leaving Scotland or rearranging their tax affairs, resulting in a drop in the tax take estimated to be around £30m.

Mackay said: ‘Analysis produced by the Scottish government showed that there is a revenue risk associated with raising the additional rate.

‘The first minister has asked the Council of Economic Advisers to consider how and to what extent this risk can be mitigated, and if we are sufficiently assured that it can be, that we consider raising the additional rate from 45p to 50p from 2018/19 onwards as part of budget considerations.’

Murdo Fraser, the Scottish Conservative’s shadow finance minister, said: ‘The SNP has already made Scotland the highest-taxed part of the UK. This damaging move would take that to a new level.

‘There is absolutely no reason why Scots should have to pay more tax than other workers across the UK. Increasing taxes will punish workers, harm the economy and raise less money, and the SNP would be making a huge mistake if it adopted this policy.’

There is already a difference in taxation between middle income earners in Scotland and south of the border, after Mackay froze the threshold for the 40p higher rate at £43,000, when it was increased to £45,000 for the rest of the UK.