A problem has been encountered with the Additional Medicare Tax calculation within QuickBooks.
Beginning January 1, 2013, employers must withhold an Additional Medicare Tax of 0.9% from wages it pays to employees that have earnings over $200,000, without regard to their filing status.
QuickBooks released an update in mid-December 2012 for this issue. However, it appears that an additional step is required for the new tax to be activated. The Payroll Setup must be opened and immediately closed.
If this was not done after the update, the employer can do it now. The “catch up” amount will be withheld from their next payroll check and will be properly withheld on future checks.