Tax book

yes you can use the same books and use intitutes study material (latest is available https://icai.org/post.html?post_id=6085 )

for any updates or changes

amendments are also there in rtp

so you need not to buy new book

all the best

If you are comfortable in understanding the amendments from the supplementary book published by ICAI then its well and good. But since there are large amount of amendments in Income Tax n service tax, you may also consider buying the new edition of the book applicable for May13 Exams. No you wont find any amendments in VAT. But whatever book you choose, do make sure that you study the amendments very very well as a good amount of questions are expected from these amendments. Good Luck for exams.