See below for the tests for a qualifying child. If you pass these tests, you are a dependent. the one that applies the most for you would be support. If you contribute $4000 to your own support, your parents must contribute $4001. You have to look at everything they spend on you. If the fair rental price of your room was $500 if they were to rent it to someone else and you pay $300, then they are contributing the other $200.
You can refer to the support worksheet:
https://apps.irs.gov/app/vita/content/globalmedia/teacher/worksheet_for_determining_support_4012.pdf
In general, to be a taxpayer’s
qualifying child, a person must satisfy four tests:
Relationship — the taxpayer’s child or stepchild (whether by
blood or adoption), foster child, sibling or step-sibling, or a descendant of
one of these.
Residence — has the same principal residence as the taxpayer
for more than half the tax year. Exceptions apply, in certain cases, for
children of divorced or separated parents, kidnapped children, temporary
absences, and for children who were born or died during the year.
Age — must be under the age of 19 at the end of the tax
year, or under the age of 24 if a full-time student for at least five months of
the year, or be permanently and totally disabled at any time during the year.
Support — did not provide more than one-half of his/her own
support for the year
