The P60 is NOW DISCONTINUED since Revenue introduced PAYE Modernisation - read the link below on how you can view your tax details on myAccount
The grey text below is for reference only
Your P60 is generated only after your employer completes the Year End process (P35) for 2015.
This is usually completed sometime in January but can be later as the deadline for P35 is Feb 15th (or 23rd if filing electronically).
If you need your P60, please ask your employer when they expect to have their signed off and complete so the P60s can be issued