Business & farm

If there is a C corporation and it did business, Form 1120 must be filed.

If you received a W-2 from the C corporation, then you must report the income you received on the W-2.

Unfortunately, given the situation as you described, you are not considered to be -self-employed and are not eligible for the self-employed health insurance deduction.

To utilize the self-employed health insurance deduction, you must be one a sole proprietor; a partner in a partnership where your earnings are subject to self-employment tax, or a 2% or more owner in an S corporation and received a W-2 from the S corporation.  A C corporation does not qualify.

See IRS Publication 535.

The following is an extract from that publication. 

One of the following statements must be true.
You were selfemployed and had a net profit for the year reported on Schedule C (Form 1040), Schedule CEZ (Form 1040), or Schedule F (Form 1040).

You were a partner with net earnings from selfemployment for the year reported on Schedule K1 (Form 1065), box 14, code A.

You used one of the optional methods to figure your net earnings from selfemployment on Schedule SE.
You received wages in 2016 from an S corporation in which you were a morethan2% shareholder. Health insurance premiums paid or reimbursed by the S corporation are shown as wages on Form W2.