If you had federal income tax withheld from your social security benefits, you enter that withholding on your tax return when you enter the SSA-1099. You are taxed on up to 85% of your social security income at your marginal tax rate whatever that rate is. If it's 12%, that is the rate you will be taxed on up to 85% of your social security income. You will get a credit on your tax return for the 7% withholding which is on 100% of your social security income.
2019 1040 line 5b is the taxable part of Social Security.
Up to 85% of Social Security becomes taxable when all your other income plus 1/2 your social security, reaches:
Married Filing Jointly: $32,000
Single or head of household: $25,000
Married Filing Separately: 0
To see the Social Security Benefits Calculation Worksheet in Turbo Tax Online version you would have to save your return with all the worksheets to your computer. Or if you are using the Desktop program you can switch to Forms Mode (click Forms in the upper right) and click on SS in the list on the left side.