Health insurance premiums are an itemized deduction in the Medical Expenses section.  The path to that section is Federal Taxes>Deductions and Credits>I'll choose what I work on>Medical>Medical Expenses.

This is confusing. The Federal Q&A about premiums says you cannot enter premiums that were pre-tax, which is correct for the Federal return.

However, at the state level premiums are post-tax and deductible. So how am I supposed to enter post-tax premiums for NY in the Federal question without the Federal return incorrectly changing? 

I also fill out a NJ return and there is a direct quesiton about insurance premiums for NJ only. Why isn't there a question in the NY return about ins premiums?

I have reviewed the instructions for New York, and I am assuming you are referring to the adjustment for the "Health Insurance and welfare benefit surcharge" as described below.

If so, you would make the adjustment in the state interview section.

You will see the following screen as you go through the state section:

Be sure to select Adjustments to federal income under the Changes to Federal Income.

You will be able to make your state-specific adjustment under the Wage and retirement adjustments section.

but what box # on the W2 or 1099R do i report on the NYS return?

If you had insurance through the NY marketplace (NY State of Health), you should have received a Form 1095-A that has to be entered into the federal section of TurboTax.   We will automatically transfer the information to your NY state return.  Here's how to enter your 1095-A in TurboTax:

1. Open or continue your return
2. Select Search and enter 1095-a
3. Select Jump to 1095-a
4. Answer Yes and enter your 1095-A info on the next screen
   • We don't need all the info from your 1095-A. We'll only ask about the info that affects your return.    @chanreunn 

no i am retired and have a W2 and 1099R. NYS form is asking to place an amount for surcharge which one is it?

Can you provide some more details about what you are entering, and what surcharge TurboTax is asking you to enter?    I had assumed you had marketplace insurance and need to report your premiums.   Each state has its own tax rules, so I want to get you the correct information.   @chanreunn 

This is what it says:

Health Insurance And Welfare Benefit Fund Surcharge

Amounts deducted for health insurance and the welfare benefit fund surcharge as reported on your:
- New York State Form IT-2102 (Copy 1), or
- Federal Form W-2 (Copy 2)

This applies to members of the:
- New York City Employees' Retirement System
- New York City Board of Education Retirement System

Yes. When you prepare your NYS return, there will be a screen that says Changes to Federal income. Go to Wage and Retirement Adjustments>NYC Retirement System health insurance or welfare fund withholding.  The very next screen will display the form you displayed. This is where you will enter the surcharge.