From 1 January 2012 the basis by which the Universal Social Charge (USC) is deducted will change from the present week1 basis to a cumulative basis. The operation of cumulative USC will mirror that presently used in PAYE. USC thresholds will be managed in the same manner in which Cut-Off-Points are presently managed in PAYE.

As a result of this change, amendments will be made to a number of PAYE forms and outputs from 1 January 2012, they include:

• Employer(s) tax credit certificate (P2C)
  
• Employees Tax Credit Certificate (TCC)
  
• The Form P60
  
• The Form P45

The Revenue On-line System (ROS) will also be upgraded to accommodate this change.

Revenue is committed to providing continual updates on this change to assist in the smooth transition from the week1 basis of deduction to the cumulative basis.

http://www.revenue.ie/en/practitioner/ebrief/2011/no-542011.html