You must fill out the Free Application for Federal Student Aid (FAFSA) in order for your expected family contribution to be determined. You must file a FAFSA for each school year by the end of June before the start of the school year. State deadlines are normally much earlier than the federal deadline, so make sure you plan accordingly. You will be notified by mail or email if you are eligible to receive the Pell Grant.
Pell Grants are determined by the student's expected family contribution, the tuition at the student's chosen institution, whether the student is full- or part-time and whether the student will attend school for a full academic year or less.
The Department of Education determines the student's expected family contribution using a formula based on the information provided in the FAFSA. According to the Department of Education, a student's expected family contribution is "the sum of: (1) a percentage of net income (remaining income after subtracting allowances for basic living expenses and taxes) and (2) a percentage of net assets (assets remaining after subtracting an asset protection allowance)."
The best case scenario is you will have a zero expected family contribution, because if you meet the other eligibility requirements, you will receive the full Pell Grant, which is $5,500 for the 2010-2011 school year.