It is essential for employers to know that RTI does not do real-time adjustments for the PAYE debt.
Each month is treated as a separate period for which interest calculation is performed. 19th of every calendar month is the last day for any adjustments/amendments you can make to the PAYE amount due for the tax month that ended on the previous 5th of that calendar month.
It also applies for Supplementary FPS or an EPS. Interest charged can be monitored on HMRC’s business tax Dashboard, however, this Dashboard can only be viewed by employers and not the agents.