The plan in which you participate through the school is not an IRA, it is a 403(b) plan. Enter amounts shown in box 12 of your W-2 only in box 12 of TurboTax's W-2 form, nowhere else in TurboTax.
Note that if you've made a special catch-up contribution such that your total contributions to the 403(b) plan exceed $27,000, TurboTax will flag this as a potential error. Ignore this error message from TurboTax.
