From April 2016 the Scottish parliament will be able to set the income tax rates to be paid by those deemed to be resident in Scotland for most of the tax year.

Tax collection will continue to be handled by HMRC, with Scottish taxpayers given an ‘S’ prefix to their PAYE tax code.

However, in a letter sent to the Public Accounts Committee (PAC) in January, HMRC's tax assurance commissioner Edward Troup wrote: ‘This has proved more complex than was initially anticipated, which is why the rating for the risk relating to this area of work has increased.’

One option under consideration is using people’s NHS details to determine their residency.

The Scottish government is currently consulting on proposed amendments to the National Health Service Central Register to allow some of the data to be shared with certain named bodies including HMRC.