9 October 2012 at 16:17
What is the value you are trying to enter into that field, for Pay Period? It's basically asking how many months of the year you worked - a number from 0 to 12, with decimals allowed in between. The periods worked must be less than the periods available to work because you can only work a fraction of the workable days. The Pay Periods box is on the employee tax certificate / IRP5 section.