HMRC is about to start updating tax codes more frequently from April 2017.
This will help HMRC collect the tax due more quickly. Any underpayments of tax identified for 2016/2017 will be collected through the 2017/2018 tax codes. But the same tax codes will also be used to collect potential tax underpayments for 2017/2018.
In July 2014, HMRC issued a consultation regarding the draft The Income Tax (Pay As You Earn) (Amendment No. X) Regulations 2014 that would have made some important changes with regards to the issue of tax codes to employees via the coding notice P2.