Calculating Mandate Fees – How to Subtract First 30?

I have 40 fulltime employees and with new business expansion (lord forbid we expand) I will have part time works that add up to 14 FTE. This means when adding 14 to the 40 I have 54 Fulltime employees putting me over the 50 limit barely. So when taking the excluded 30 fulltime employees in to consideration do I take that from the 54 FTE or the 40 fulltime? Will I pay 2000.00 for 10 employees or for 14?