You may be picked for verification and the verification sheet will ask for SSD income information. Don't worry, being chosen for this DOES NOT mean that your daughter's assistance is in jeopardy or that you did anything wrong. Its either a random choosing or from some answer on the form they can see there is income that is not included (again, not your mistake but because there is no where on the fafsa form to put the info) and that put up a red flag. You will just fill out the form and turn in a copy of your taxes. The financial aid office will complete the process of verification and then let you know if there were any corrections necessary on the fafsa. This may or may not change your EFC.
The website said something like 25% of all submissions end up getting a request for verification.
I noticed on DS's application that you could register for Selective Service linked right from the form. I forgot about him needing to do that. He isn't 18 yet so we didn't do that.