Box 16 is blank, but your form shows that state tax was withheld in Box 14, your tax software may prompt you to fill it in. In most cases, you should use one of the following amounts:
Use the taxable amount: If Box 16 is blank, you can often enter the amount from Box 2a. This is the most common approach.
Use the gross distribution amount: If Box 2a is also blank, and you did not make any after-tax contributions to the account, you may use the amount from Box 1.
