255. Such sums, as Parliament may by law provide, shall be charged on the revenues of India in each year as grants-in-aid of the revenues of such States as Parliament may determine to be in need of assistance, and different sums may be fixed for different States:
Provided that there shall be paid out of the revenues of India as grants-in-aid of the revenues of a State for the time being specified in Part I of the First Schedule such capital and recurring sums as may be necessary to enable that State to meet the costs of such schemes of development as may be undertaken by the State with the approval of the Government of India for the purpose of promoting the welfare of the scheduled tribes in that State or raising the level of administration of the scheduled areas in that State to that of the administration of the rest of the areas of that State:
Provided further that there shall be paid out of the revenues of India as grants-in-aid of the revenues of the State of Assam sums, capital and recurring, equivalent to-
(a) The average excess of expenditure over the revenues during the three years immediately preceding the commencement of this Constitution in respect of the administration of the tribal areas specified in Part I of the table appended to paragraph 19 of the sixth Schedule; and
(b) The costs of such schemes of development as may be undertaken by that State with the approval of the Government of India for the purpose of raising the level of administration of the said areas to that of the administration of the rest of the areas of that State.