Maybe. Your retirement income from WI public schools (Wisconsin State Teachers retirement systems) is not taxable on your WI state tax return if:

1. You were retired from the system before January 1, 1964, or
2. You were a member of the system as of December 31, 1963, retiring at a later date and payments you receive are from an account established before 1964, or
3. You are receiving payments from the system as the beneficiary of an individual who met either condition a or b.

See below for more information.

According to revenue.WI.gov:

Are my retirement benefits taxable??

• If you are a full-year resident of Wisconsin, generally the same amount of your pension and annuity income that is taxable for federal tax purposes is taxable by Wisconsin.
• If you are a nonresident of Wisconsin, your pension and annuity income is generally nontaxable by Wisconsin.
• If you are a part-year resident of Wisconsin, the pension and annuity income you receive while a Wisconsin resident is generally taxable in the same manner as it is for federal tax purposes. The pension and annuity income you receive while a nonresident is generally nontaxable.
  
  

Exceptions to the taxation of retirement income described above are as follows:

• Social security benefits are not taxable by Wisconsin.
• Payments received from the retirement systems listed below are not taxable by Wisconsin provided:
  
  
  1. You were retired from the system before January 1, 1964, or
  2. You were a member of the system as of December 31, 1963, retiring at a later date and payments you receive are from an account established before 1964, or
  3. You are receiving payments from the system as the beneficiary of an individual who met either condition a or b.
     
     

  The specific retirement systems are:

  Local and state retirement systems: Milwaukee City Employees, Milwaukee City Police Officers, Milwaukee Fire Fighters, Milwaukee Public School Teachers, Milwaukee County Employees, Milwaukee Sheriff, and Wisconsin State Teachers retirement systems.

  Federal retirement systems: United States government civilian employee retirement systems. Examples include the Civil Service Retirement System and the Federal Employees' Retirement System.

  Note: The following payments are not exempt from Wisconsin income tax:

  • Payments received as a result of voluntary tax-sheltered annuity deposits in any of the retirement systems listed above.
  • Payments received from one of the retirement systems listed above if you first became a member after December 31, 1963. This applies even though pre-1964 military service may have been counted as creditable service in computing your retirement benefit.
  • Payments from the federal Thrift Savings Plan.
    
    

  Caution: Only retirement benefits based on qualified membership in one of the retirement systems listed above may be subtracted from Wisconsin income. Qualified membership is membership that began before January 1964 as explained above. Any portion of your retirement benefit that is based on membership in other retirement systems, or based on employment which began after December 31, 1963, is taxable and may not be subtracted from federal income.

• Military and uniformed services retirement benefits are not taxable for Wisconsin tax purposes.
• Railroad retirement benefits are not taxable for Wisconsin purposes.
  
  

Note: Payments you receive from a nonqualified pension or annuity or a nonqualified deferred compensation plan are taxable by Wisconsin when received by a Wisconsin resident. Such payments may be taxable or may be exempt when received by a nonresident of Wisconsin. For more information on this issue, see Wisconsin Publication 106, Wisconsin Tax Information for Retirees, and Wisconsin Publication 126, How Your Retirements Benefits are Taxed.

https://www.revenue.wi.gov/pages/faqs/pcs-retired.aspx