I think it depends on what type of retirement plan (pension, annuity, 401k, IRA, etc.) you received income from last year, and what state you're filing from. If the distribution came from after-tax contributions, you may already have paid state tax on that money, and don't have any further state tax liability for it. Check boxes 5, 7, 9a and 9b to make sure your have correct entries in those first. If all looks correct, box 16 might be "0."
