Dear Mr. Jain,
As you have pointed rightly out, Clause 2(1) of Chapter- II of the Finance Bill, 2012, mentions that the rates of tax specified in Part I of the First Schedule will be applicable for the assessment year commencing from the 1st day of April, 2012. The Officials in their "Copy-Paste" hurry would have forgotten to change the date. It is a copy of the paragraph that appeared in the Finance Bill,2011.
If you see the second line of the Finance Bill, 2012, it states "A Bill to give effect to the financial proposals of the Central Government for the financial year 2012-2013". This means that the assessment year mentioned in Clause 2(1) of Chapter- II of the Finance Bill, 2012 should be "1st day of April, 2013" and not 1st day of April, 2012.
Let us forgive the Finance Ministry Officials for the typographical error. If they have noticed this error, they can recrify the same by issuing an "ERRATA".
Ananthanarayanan. P. V.