Are you referring to the Iowa Public Employees' Retirement System?
If you make elective deferrals then those would more than likely be shown in box 12 of the W-2 probably with a code of E.
Check box 14 of your W-2 too
....I've been poking at the IPERS site, and they claim it is a Defined Benefit plan with both employer and personal contributions.... that sounds more like a 414(h) plan...but they don't say that exactly, so I'm unsure.
IF you are entering your W-2 into the software, you just enter the data it shows on your Paper W-2 form
________________
IPERS Employers Handbook:
When completing the Form W-2 for IPERS-covered employees, follow
these procedures:
• STEP 1 Check Box 13, Retirement Plan, as IPERS is a qualified plan under
Internal Revenue Code section 401(a).
• STEP 2 (Optional) You may report the amount of the member’s IPERS
contributions in Box 14. This amount should have been withheld pretax from
the member’s paycheck
...and if you do see your "required" IPERS contributions listed in box 14, for the TTX software's tax category, I believe you will use "Other not on above list"
( Subject to someone correcting me as I am a bit unsure @dmertz ?)
I don't think your IPERS contributions have any effect on your tax return. They are pre-tax contributions for both federal and state, so the amount of your IPERS contributions is already excluded from box 1 of your W-2. You don't get any additional deduction for it on your tax return. Any indication in box 14 of your W-2 regarding your IPERS contributions would just be for your own personal information (although you should still enter it into TurboTax as Steam_Train indicated).