Social security only becomes taxable when added to sufficient other income, including your spouse's income. If you are otherwise required to file a tax return, you do need to enter it in Turbotax (TT). TT will determine the taxable portion.
Social security (including SSDI) becomes taxable when your income, including 1/2 your social security, reaches:
Married Filing Jointly(MFJ): $32,000
Single or head of household: $25,000
Married Filing Separately and lived with your spouse at any time during the tax year: $0
After TurboTax (TT) calculates the taxable portion of SS, it puts the total amount of SS on line 5a of form 1040 and the taxable amount on line 5b. TT also produces a worksheet to show how the taxable amount is calculated. Although most people pay tax on 85% of their SS. it can be less for lower income taxpayers.
You may be thinking that filing Married Filing Separately (MFS) is going to save you money, because you won't have to add your spouse’s income to your return. That thinking is usually wrong. There is a special rule that says SS becomes taxable at zero ($0) other income when Filing as MFS. The doubled standard deduction will usually wipe out all the spouse’s income, on a joint return. But you will still get the use the lower joint filing rates.
Before making a decision to file as MFS, you should run test returns and compare. You can use this tool: https://turbotax.intuit.com/tax-tools/calculators/taxcaster/?s=1
