1. I'm a bit confused. You "believe it is an amended Form 1040x" that you are preparing, are looking at?

Yes, I am preparing a 1040X to report a missed entry of a W2:  Gross Wages (Box1), SS Fica Wages (Box 3), Medicare Wages (box 5) are all $20k; SSA FICA Tax Withheld (Box 4) $1,240.00; Medicare Tax Withheld $290.00.

2. "Am I correct in saying taxpayer paid full FICA Tax on the Original Form 1040, Schedule C Net Profits?"

Yes, Form 1040, Schedule C Net Profits approximately $250k, forgot to include the W2 from Bullet #1.

3. We cannot see their form(s). You would confirm the data and do some math. Your issues for Sched 1 and 2 are the same issue; you would confirm if that data is correct for the additional tax owed and for the deduction for the 50% owed.

    a. Understand and realize that I am not digging into the details of the entire Schedule SE. For instance, when I did reference the 92.35% adjustment in an earlier post, it seemed to confuse the situation so I jumped ahead within the equations of Sch SE. Trying to simplified by discussing only the FICA Wage Limitation & corresponding Tax. Realize Medicare Wages and tax is also done on Sch SE but that was not relevant to the Refundable Excess FICA Tax problem. ProSeries is making all of those calculations, nicely;

    b. Here are the math calculations from the above data:

Schedule C Net Profit $251,760

92.35% adjustment     $232,500

Max SS Wage Limit    $132,900 (where I started in my beginning post since the first two numbers irrelevant to the mathematical mechanics until this point.)

    The original filed Form 1040, Schedule SE, Part 1 Short Form A ($132,900 x .062 employee share/portion of FICA Tax already adjusting for 50%) = $8,239.80 rounded up to $8,240.00.

    The Amended Form 1040X, Schedule SE, Part II Long Form B ($132,900 - $20,000 W2 Employee Fica Wages) = $112,900 Adjusted FICA Wage Limit applied to Schedule C Net Profit. Next step $112,900 x .062 = $6,999.80 + $1,240.00 W2 Fica Tax =$8,239.80 rounded up to $8,240.00.

(The employer share of 6.2% of $112,900 = $8,240.00) Combined FICA Tax = $16,480.00

     Yes, the numbers are the same when comparing the Originally Filed Calculation to the Amended Calculation.

     Yet, in my humble opinion, taxpayer already paid on Sch SE, Part 1 Short Form A the difference of $1,240.00 via Schedule C Net Profit - the amount already on Form W2. Is my opinion correct?

     If my humble opinion is correct, then there would be Refundable Excess FiCA Tax of $1,240.00.

     Does the Refundable Excess FICA Tax claim on Form 1040, Schedule 3, Part II, Line 11 (a. Smart Worksheet for Excess Social Security and Tier 1 RRTA Tax Withheld)? As I mentioned before, IRS Publication specifically discusses two W-2s from two different Employers. Current/Prior years, I have other clients claim Excess FICA Tax many times so I understand that ProSeries makes that calculation easily. On the other hand, IRS Publication says to file refund on Form 843 if the scenario is not 2 W2s from 2 different employers. Yet, in my humblest opinion, the Schedule C Net Profit is the driving force causing the Excess Fica Tax Withheld. In years, past when the W2 was properly and correctly entered no Excess because the Sch SE Part 2 Long Form B calculates the equation perfectly!

Hopefully, this gives y'all more clarification and understanding of this case situation.