Income tax - appeal - is itpossible to file an appeal

Dear Friends

Pl go thor' the few lines ..

Asst Year  2009-10  date of asst oreder recd by assessee:27.10.2011

Asst Completed u/s 143[3] afterdue notice issued u/s143[2]

Additions made during asst proceedings to the tune of 20,00,000/- and  assessee /his Auditor signed on the case sheet with no protest and as such it an agreed addition

No appeal is filed. Now assessee wants to file appeal with CIT [A] As now he finds tax on additon is more to his status.

Can I file an appeal with cit [a]  

pl come with suitable answer and any case law reference please

Thanks in advance

Thanking you