HMRC explained that while, as noted above they are developing RTI there are three issues with that –
it does not include self-employed income, which is about 16 or 17 per cent of the income tax receipts;
with our pay-as-you-earn codes, we sometimes adjust for things that are not relevant to Scottish income tax so the amount of tax that is being deducted through PAYE is not always precisely the same as what the Scottish income tax outturn will be;
the information is based on the S code each month.