2005 2nd Quarter 3% 2005 3rd Quarter 3% 2005 4th Quarter 3% 2006 1st Quarter 3% 2006 2nd Quarter 4% 2006 3rd Quarter 4 2006 4th Quarter 5% 2007 1st Quarter 5% 2% higher for interest paid on refunds 4% higher effective July 1, 1995 on overdue taxes, penalties, interest, insufficient installments, CPP and EI premiums.