The consultation was announced at the Budget and is seeking views on the use of income tax relief for employees’ business expenses, including those that are not reimbursed by their employer, such as business phone calls or use of personal cars.

HMRC says the main aims of the call for evidence are to understand whether the current rules or their administration can be clearer and simpler; whether the tax rules for expenses are fit for purpose in the modern economy; and why the cost to the exchequer of the tax relief for expenses which are not reimbursed has increased.

The tax relief on expenses which employers do not reimburse and employees then claim from HMRC costs the Exchequer £800m per year, and there has been a 25% increase in claims between 2009-10 and 2014-15.

HMRC says the government has no plans to remove the relief on employee expenses, but that given the size and importance of the relief, it does want to understand the use of the relief better.

The consultation offers a list of 17 questions covering the kinds of expenses claimed, company policies, views on the operation of the current system and suggestions for future changes.

The new deadline for responses is 10 July.

Open consultation: Taxation of employee expenses call for evidence is here.