If your income is low enough, your social security will not be taxable. It would appear on 20a to show the amount received but Line 20b would be blank. As for your dependent, look on line 6c. Again, if you income is too low, having a dependent doesn't benefit you.
An easy way to check to see if it is all entered on that line. You may view your 1040 by following these steps.
- Go to My Account
- View Tax Summary
- Preview my 1040