Treatment of Capital Gain in Tax Return Filing

Dear Sirs,

                   plz guide me in this matter

                  Suppose  an assessee sells his house for Rs.10,00,000 in F.Y.2010-11 (say Mar,2010)

                  Now if he plans to invest the entire proceeds of Rs.10,00,000 in buying another House Property in the F.Y.2012-13 (say Jan,2012) 

                 then what treatment shall be adopted by him in respect of FILING HIS INCOME TAX RETURN FOR A.Y.2011-12

(with respect to the proceeds of Sale of House Property ,i.e. should he pay tax on the Capital Gain on sale of House Property in the current year since he has invested the proceeds in F.Y.2012-13)