Where on self employment can I deduct Medicare Part B?

The deduction for health insurance if you are self-employed is not a business expense on Schedule C.  It does not reduce your profit from your self-employment.  Only health insurance for employees is deductible as a business expense.  Instead, it is a deduction on Form 1040 Schedule 1.  In order to take a deduction for your health insurance if you are self-employed, you must have a profit from your self-employment.  The deduction is limited to the lesser of your profit, or the cost of your insurance.  To deduct your Medicare insurance, if you are self-employed:

1. Open or continue your return.
2. Navigate to the Schedule C section:
   • TurboTax Online/Mobile: Go to Schedule C.
   • TurboTax Desktop: Search for Schedule C and select the Jump to link.
3. If this is your first time entering info about your self-employment work, you’ll be asked some initial questions.
   • If you previously entered info on your self-employment work, select Edit next to the type of work you entered previously.
4. On the Select the expense categories you have screen, select Less common to show all expense categories. Browse the options and select Health insurance premiums, then select Continue.
5. On the Expenses section, find the Health insurance premiums section and select Start.
6. On the Tell us about health insurance premiums for your [business] work screen, enter the total amount of health insurance premiums you paid.

For more information, see Where do I enter my health insurance premiums if I'm self-employed?

Do you get it deducted from your Social Security checks?   Go back and delete it from the SSA-1099 entry screen and enter it under your self employment business.  Try going to the search box by My Account and type in Social Security Benefits. That will give you a Jump To link to take you directly to it.

Self-employed health insurance deduction goes on Form 1040 Schedule 1 line 17 (then to 1040 10), 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 and the remainder gets added in to medical expenses on Schedule A.

Where to enter Health Ins if you are self employed. (COBRA goes on schedule A)
https://ttlc.intuit.com/turbotax-support/en-us/help-article/insurance-medical-benefits/enter-health-insurance-premiums-self-employed/L8bO3dyWi_US_en_US?uid=lky76pdq

For Home & Business Desktop program…..
On the Business tab Click on Business Income and Expenses Update
Click on Edit by your Business
Then under Business Expenses
Go to Other Common Expenses - Insurance Payments