According to IRS:
If you were self-employed and paid for health insurance, you may be able to deduct any premiums you paid for coverage for any child of yours who was under age 27 at the end of the year, even if the child was not your dependent.
Taxpayers can claim the self-employed health insurance deduction if the insurance plan is established under their business and if one the two items below is true:
1. They were self-employed and they had a net profit.
2 They received wages from an S corporation in which the taxpayer was at least a 2 percent shareholder.