When filing taxes online, make sure that you fill out your W2s accurately. Forgetting to check the Retirement Fund part of Box 13, when the funds for that box are mentioned in Box 14 will make your returns eligible for rejection.
Teachers in public schools do not pay into Social Security. Instead, they pay into the Teacher Retirement Fund. I got all of my numbers right but completely missed 1 little check box. So, my state return came back rejected. When I tried to log back in to change the W2, it would not let me change it. Eventually, I realized that since the W2 is a shared document between my state and federal return, I will not be able to change it until my federal return is rejected as well.