Yes, you have to enter the P45/Starter Checklist Details for new Employees'. In case you have not entered the details you will receive an error message when you E-File the FPS return and your FPS E-Filing will not be accepted.For more information click on the link https://www.gov.uk/new-employee/employee-information

To Rectify this problem you need to enter the P45/Starter Checklist details of your new Employees' in the View/Edit Employee P45/Starter Checklist details section, rollback the pay periods processed for the new Employees' and continue to re-run the periods you rolled back for the new employees'. Further E-File the FPS again and your FPS will be successfull.