What exactly do you have to enter upon signing up? Also, will it make you fill out a tax form (1099) even if you made way less than $600?
Have a look at my adsense application tutorial for step by step guidelines. You will have to fill out a tax form once your site/blog is accepted.
Tax info is only collected if you're located in the US I believe. You can read about what to expect by reading their Terms of Service when you apply.