Running real time reporting for payroll and PAYE has been mandatory for some time now yet still a huge number of people are being caught out, normally through not using an up to date system, but also through changes in legislation to how dividends are taxed, new pension rules and the increasing likelihood of individuals having income (no matter how small) from other sources.
We've noticed HMRC are fiddling around with tax codes for a lot of people of late much more frequently than was the case in years gone by. You could say that's an attempt on their part to collect tax from individuals as quickly as possible and I think that's largely what they are doing. Their argument would be that they are trying to be as accurate as possible, but I'm not wholly convinced by that although as long as payroll is being properly administered then amounts paid under PAYE would be pretty close to the correct tax payable figure for an individual.
The real time reporting of payroll is very much in sync with IR35 legislation and I would imagine flags are raised at HMRC if there are inconsistencies with what HMRC’s software is apparently able to recognise.