Builder is asking 33% income tax on difference amount of gov

Dear All,

I had buyed a flat in Pune. 

My Agreement cost is lower then Goverment Valuation.

Now builder is asking to pay 33% income Tax on the difference amount of the Goverment Valuation & the Agreement Cost.

for Eg (Agreement Cost is 28 Lacs & Goverment Valuation is 31 Lacs, so builder is asking to pay 33% cash as Income Tax on the difference amount ie - 3 Lacs)

so, it there any rule of goverment....

Please suggest.

Regards,

Jitendra.