If you are adding new starters to the system and have noticed that you are able to progress past the Eligibility to Work screen without adding all details, you can make these mandatory by editing a Global setting.
To do this:
Go to Setup and click Settings.
Click System Settings, then Global.
Search Eligibilty To Work: All Details Mandatory On New Starter and click it.
Tick the Boolean box and select True from the dropdown.
Click Save.