HMRC’s computer systems will be able to calculate very accurately—indeed, to the penny—how much of the payover made by an employer or self-assessment taxpayer is attributable to the Scottish rate, and the auditors will be able to check that that routine works as expected.The issue of disaggregation will apply to the 1 per cent in which the money comes in as a result not of automatic income tax processes, including self-assessment taxpayers sending their cheques or making their credit transfers...