According to the IRS Instructions for Form 1040, page 24:
If your pension or annuity is fully taxable, enter the total pension or annuity payments (from Form(s) 1099-R, box 1) on Line 4d; don't make an entry on Line 4c.
If your Form 1099-R shows a taxable amount, you can report that amount on line 4d. But you may be able to report a lower taxable amount by using the General Rule or the Simplified Method or if the exclusion for retired public safety officers, discussed next, (in Form 1040 instructions) applies.
You can also access those instructions in TaxAct, by clicking on Form Instructions
on the right hand side of the screen.