Self-employed health insurance deduction goes on Form 1040 Schedule 1 line 16 which flows to 1040 line 8a as long as the expense is not greater than your Net Profit on Schedule C individually. If the insurance is more than your Net Profit on each of your Schedule Cs you can split it up and enter part on each Schedule C so you don't go over the Net Profit on either one.
Self-employed health insurance deduction goes on Form 1040 Schedule 1 line 16 then to 1040 line 8a, as long as the expense is not greater than your net self-employment income. 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 line 16, and the remainder gets added in to medical expenses on Schedule A.
BUT do not enter any Health Care Marketplace insurance you bought. If you enter the 1095-A and select the "Self-employed and bought a Marketplace plan" box, it will automatically include those premiums in the SE Health Insurance section. So you shouldn't enter it again on schedule C.
