It is in your interest to return the forms without delay, as Revenue may take you to court if you do not lodge end-of-year returns within the proper time. If you fail to lodge the end-of-year returns in time, an employee may find it difficult to obtain social welfare benefits later on.
If your end-of-year returns are not complete, you may get them back for completion. So it is in both your and the employee's interests to ensure that you lodge accurate end-of-year returns in time.