S-corp owner healthcare premium deduction up to medicare wage or Box1 of W2?

[Lakeview88]

I am 100% owner of an S-corp.   My W2 Box 1 wage amount ($10,000) is significantly lower than my Medicare/Social security wage ($22,000) since I contribute to a self-employed 401k plan.   I have paid $15,000 in healthcare premium total for the year.   Can I only deduct up to 10K for the self-employed health insurance premium deduction or could I deduct up to 15K (since it is under 40K medicare wage limit)?   I cannot find any clear documentation for this, except you can deduct up to your S-corp wage amount for this.   But which wage - Box 1 in my W2 or Box 5 (Medicare wage)?

[JulieS · Accepted solution]

This deduction is based on your W-2 box 3 wage amount. 

The instructions for Schedule 1, line 17 explain how the deduction is calculated.

Click here for more. 

[Lakeview88]

Thank you @JulieS , very helpful!