Generally, you do not report contributions to your 403(b) account (except Roth contributions) on your tax return. Your employer will report contributions on your Form W-2. Elective deferrals are reported in Box 12 and the Retirement plan box will be checked in Box 13. If you are a self-employed minister or chaplain, see the discussions below.
Per the IRS website 403(b) Plan Basics:
To enter the deduction in your TaxAct® return:
Refer to IRS Publication 560 Retirement Plans for Small Business to determine the contribution amount that can be deducted on Schedule 1 (Form 1040), Line 28.
Chaplains. If you are a chaplain and your employer doesn’t exclude contributions made to your 403(b) account from your earned income, you may be able to take a deduction for those contributions on your tax return.
However, if your employer has agreed to exclude the contributions from your earned income, you won’t be allowed a deduction on your tax return.
If you can take a deduction, include your contributions on Schedule 1 (Form 1040), Line 36. Enter the amount of your deduction and write 403(b) on the dotted line next to Schedule 1 (Form 1040), Line 36.
To enter this in your TaxAct return: