As DoninGA implies, if you enter Forms 1099-R correctly TurboTax produces the correct result on Form 1040 line 4b. After entering the Form 1099-R and answering the questions that immediately follow, you must also click the Continue button on the page that lists the Forms 1099-R and answer any questions that apply to your Forms 1099-R in aggregate.
In what way is the amount on Form 1040 line 4b different from what you expect?
What is the code in box 7 of the Form 1099-R that you received for the distribution that you expect to be reported (or not reported) on Form 1040 lines 4a and 4b? Is the IRA/SEP/SIMPLE box marked?
