The Expected Family Contribution is a federal calculation that colleges use to determine the amount of student aid a student is eligible to receive for an enrollment period. Typically, EFC is calculated once for the academic year based on the Free Application for Federal Student Aid (FAFSA) and financial aid is awarded using this number. The formula used to create this index number includes a family's household size, number of people attending college at least half time, income (both taxed and untaxed), assets, and some benefits like Social Security and unemployment.