Question about Gender Identity

[dreamsofpaprika.livejournal.com]

I have a question for the people here at transgender: If you are filling out a survey (for example, in school) and you are trans, how do you decide what box to check off according to your sex? Do you check off the box for the sex you identify with or the sex they have you registered as?

For example, if you are a MTF (male to female) transgender, do you check off the box corresponding with female (which is technically the gender you identify with) or the box corresponding to male (the gender you are registered as). Because technically, young trans people cannot transition legally just yet (that's why so many buy illegal hormones). So, if you are not transitioned legally, you are technically still registered as your biological gender- even though you may not identify with it. This may cause some issues with the trans individual. Having society force you to be a gender you don't feel comfortable with, especially having that society tell you who you are. Shouldn't you know who you are? Obviously, you know yourself better than THEY do, right? It is a great dilemna when checking off gender in a  survey or test in school. I know some trans people actually try to cope with their biological gender by living up to that gender, though unhappy they may be.
 
So what gender would be appropriate to confirm during these tests or surveys? Your identified or biological gender?

Any thoughts?