I agree with Mr. Vikas Vishwakarma
First your capital gain is (rectify me if wrong)
If Purchased during (1-04-94 - 31-03-95)
Sale consideration = 47,50,000
Less INDEXED Cost of purchase (assumed included any taxes paid ) = (5,00,000) X 632 / 259
Less indexed cost of improvement = Not mentioned (assuming nil)
35,29,922 =a
If Purchased during (1-04-95- 31-03-96)
Sales consideration = 47,50,000
Less (same as above) = (5,00,000 X 632 / 281)
36,25,444 =b
You need to invest amount of cap gain, not the sales consideration
If you do not make investment or withdraw the amouint then taxable amount is 20% of the capital gain
As mentioned by Mr. Vikas
If the construction completes within the said period of 3 years after the transfer
or if you purchase within 2 years after transfer or 1 year before transfer
The property should be CONSTRUCTED within the prescribed time , you can later IMPROVE IT
Suppose you build 2 floors (in my opinion construction is completed) lateron you can construct another floor and its cost will be allowed as Cost/ Indexed cost of acqusistion will calculating Capital gain for sale of That or Part of that property
Allocate your expenses . If its not possible to complete the construction within desired time and such a hypothesis (which I mentioned) is possible then ask the contractor to adjust the bill . Like take more money now (to the extent of cap gain) and charge less on the IMPROVEMENT/REMAINING PART