Certain amount to be added or deducted from contribution leviable from a person.

The amount by which the total value of the plots included in the final scheme with all the buildings and works there on allotted to a person falls short of, or exceeds the total value of the original plots with all the buildings and works thereon of such person shall, as the case may be, be deducted from or added to the contribution leviable from such person, each of such plots being estimated at its market value on the date of the declaration of intention to make a scheme or the date of a notification under section 63 and without reference to improvements contemplated in the scheme other than improvements due to the alteration of its boundaries.