On or before 17 December 2014 17 December 2014 to 31 March 2018 1 April 2018 and after Tax Charge
Ar 17 Rhagfyr 2014 neu cyn hynny 17 Rhagfyr 2014 i 31 Mawrth 2018 Ar 1 Ebrill 2018 ac ar ôl hynny Tâl Treth