(1)For each budgetary period, the Welsh Ministers must by regulations set a maximum total amount for the net Welsh emissions account (a “carbon budget”).
(2)The Welsh Ministers must ensure that the net Welsh emissions account for each budgetary period does not exceed the carbon budget for that period.
(3)The budgetary periods are—
(a)2016 to 2020, and
(b)each succeeding period of five years, ending with 2046 to 2050.
(4)The Welsh Ministers must—
(a)set the carbon budgets for the first two budgetary periods before the end of 2018, and
(b)set the carbon budget for the third and later budgetary periods at least five years before the start of the period in question.