That's not something you would enter in Box 12. If you have no state tax withheld, just leave the field blank. After you enter the form, there is a series of questions you have to answer. Depending on your state, there may be questions about the source of the distribution that would result in the money being nontaxable in your state. Rather than asking this in the Federal program, there may be questions in the state program asking about your pension income and whether it is taxable or not. Just keep going to answer all questions inthe Federal and , later, all questoons in the state.