Excess Social Security when paid via w2 and 1099

Lets say we have w2 employment that well exceeds social security withholdings. Taxpayer also receives significant commission income via 1099 to his LLC. There should not no Social Security liability on the 1099 earnings as the max was already met, only a Medicaid liability.

 

1. How does Intuit manage this situation in turbo tax desktop?

2. If the return was previously fiied and extra social security was paid for the LLC income, I suspect a form 843 needs to be submitted (and not an an amended return). Does Turbo Tax support this?