The entire amount of your federal retirement is excluded from NY tax. See page 11 of New York Publication 36 and the New York State Department of Taxation and Finance link.
"Qualified pension benefits or distributions received by officers and
employees of the United States, New York State, and local governments
within New York State, are exempt from New York State, New York City,
and Yonkers income taxes."
" This subtraction modification is allowed
regardless of the age of the taxpayer or of the form the payment(s) take.
11
Publication 36 (3/15)
This subtraction modification is allowed for a pension or distribution
amount (to the extent the pension or other distribution was included in your
federal adjusted gross income), including a distribution from a pension plan
which represents a return of contribution in a year prior to retirement, as an
officer, employee, or beneficiary of an officer or an employee of:
• The United States, its territories, possessions(or political subdivisions
thereof), or any agency, instrumentality of the United States (including
the military), or the District of Columbia."
I can see where the wording above can be confusing when it says "including a distribution from a pension plan which represents a return of contribution...." but the fact remains that your federal pension isn't taxable in NY. The link above says it more clearly:
Information for retired persons
Pension and annuity incomeYour pension income is not taxable in New York State when it is paid by:
- New York State or local government
-
the federal government, including Social Security benefits
- certain public authorities