My parents are divorced. Which parent is responsible for filling out the FAFSA form ?

If your parents are separated or divorced, the Custodial parent is responsible for filling out the FAFSA. The custodial parent is the parent with whom you lived the most during the past 12 months. This is not necessarily the same as the parent who has legal custody. If you did not live with one parent more than the other, the parent who provided you with the most financial support should fill out the FAFSA. This is probably the parent who claimed you as a dependent on their tax return. If you have not received any support from either parent during the past 12 months, use the most recent calendar year for which you received some support from a parent or lived with either parent.