HMRC have slipped this procedural change in largely unnoticed. Not unnoticed to the eagle eyes of the ICAEW however.
The main change is that taxpayers who are due a repayment for 2015/16 will no longer be sent this automatically shortly after the P800 is issued. Instead they are encouraged to go into their Personal Tax Account (PTA) and submit their bank details to get a refund. If they prefer they can phone HMRC and ask for a refund. If they do neither of these things, HMRC will send the refund after 45 days.