TurboTax on-line does not provide the Social Security worksheet in order for you to determine if your social security earnings are taxable.  I have attached Notice 703, which is a worksheet that helps you make that determination.

Generally, if social security is your only income, then it is not taxable.  However, if your combined income is above a certain limit ($25,000 for Single, Head of Household, and Qualifying Widow or Widower with a dependent child; $25,000 for Married Filing Separately; $32,000 for joint filers who lived together for any part of the year.) then at least some of the social security is included as taxable income.