After you enter the information from the Form 1099-R that reports the distribution from your teacher pension, continue through the tax interview. TurboTax will ask Where Is This Distribution From? Select Public Pension received from a federal, state, or local government. (Click the first screenshot below for reference.)
When you are in the Missouri state tax interview (several screens in), you'll come to a section for Missouri Pension and Retirement Adjustment. You'll see that TurboTax has automatically calculated the pension deduction for you. (Click screenshots 2-5 below for reference.)
For more information, please click this link: Am I eligible for a
MO pension exemption?
