If you are considering applying for financial aid, you must file the FAFSA. Your family can use last year's taxes to "guestimate" the numbers for this year. There is an opportunity later to adjust the numbers once your taxes for this year are completed. DON'T WAIT! Once the money has been given out, your opportunity for financial assistance is gone.
The CSS Profile is another financial form that might be required, so check with the colleges that you have applied to and see if you must complete this form, as well.