How much can a 17 year old earn without paying taxes?

Assuming that the person in question is single, childless, and still a dependent for tax purposes, s/he can earn $5,450 in 2008, $5,700 in 2009 -- the standard deduction for a single person -- without incurring federal income tax liability. Please note that "earned income" is exactly what it sounds like: income actually worked for. If s/he has "unearned income" (usually interest or dividends, maybe capital gains) of more than $900 s/he must file a return and may owe federal income tax.