One employee was missing a postal code.  When the T4s were printed, no error was noted and the T4 printed correctly.  When the data was exported, this one T4 slip was not included in the data and resulted in a discrepancy notice from CRA, which means the client will incur a $100 late filing penalty.  This needs to be corrected ASAP!  Luckily, in this case it was only one employee affected.  There can not be a discrepancy in the printed T4s and the exported data!