When the Settlement-officer decides, under section seventy-three or section seventy-four, that land which has been held free from revenue, or at less than a full assessment, is liable to pay revenue, or to pay the same at enhanced rates, such decision shall take effect from the first day of the agricultural year next ensuing; unless the Chief Commissioner directs that the amount payable in respect of such land on account of the revenue accruing due within anyone or more of the last preceding twelve years shall be realized.