For the first 3 months of 2012 there was a freeze on the RCT withholding tax rates at either 0%, 20% or 35%. That arrangement is now finished and with effect from 1 April 2012 the withholding tax rates applied to subcontractors can change at any time depending on their compliance record.
Where there is a change in RCT rates, Revenue will advise both the subcontractor and the principals invovled.
Subcontractors can request a review of the RCT rate applied to them via ROS or by contacting their local Revenue Office.
For more information on this see Revenue website at http://www.revenue.ie/en/practitioner/ebrief/2012/no-142012.html.