Whilst there is a need to use the counteraction notice procedure, the tax charged will continue to be assessed through a closure notice where there is an open enquiry, or by a WRA assessment.
Er bod angen defnyddio'r weithdrefn hysbysiad gwrthgyfeirio, bydd y dreth a godir yn parhau i gael ei hasesu drwy hysbysiad cau pan fo ymchwiliad agored, neu drwy asesiad gan yr Awdurdod Cyllid.