Self-employed health insurance deduction goes on Form 1040 Schedule 1 line 16, as long as the expense is not greater than your self-employment Schedule C Net Profit minus the deductible part of the SE tax (from Schedule 1 line 14) and any business retirement plan contributions on line 15.
Then schedule 1 line 22 Adjustments to Income goes to 1040 line 8a.
If it does exceed your net self-employment income it gets split automatically. An amount equal to your net self-employment income goes on Form 1040 Schedule 1, and the remainder gets added in to medical expenses on Schedule A.
