The forecast of costs (until 2018-2019) is for introducing the SRIT, which will start on 6 April and will affect 2.6 million Scottish taxpayers.
The Scottish government reimbursed HMRC £1.7m of the cost of introducing the Scottish rate during 2014-2015.
The NAO said that HMRC’s preparations for the Scottish rate had been “thorough” and that modifying existing IT capability had “minimised the risks and costs associated with the need to develop an entirely new system to administer the [Scottish rate].”
But the NAO also said that HMRC had only put “limited resources” into planning for potential tax loss as a result of the Scottish rate. “Given the significance and complexity of the [Scottish rate] project, HMRC will need to react quickly to the changing compliance environment within the UK from April 2016,” it said.
From 6 April, the income tax rates set by the UK government that apply to the ‘rest of the UK’ will be reduced by 10p in the pound for Scottish taxpayers, and increased by the [Scottish rate].