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 Line 28 of Federal Form 1040.
Chaplains. If you are a chaplain and your employer does not 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 will not be allowed a deduction on your tax return.
If you can take a deduction, include your contributions on Line 36 of the Form 1040. Enter the amount of your deduction and write 403(b) on the dotted line next to Line 36.
To enter this in your TaxAct return: