If you already filed a 2017 Tax Return, you will need to Amend the return to include your pension income. You can click here for instructions on Amending your tax return: How to Change a Tax Return You Already Filed.
If you haven't already filed a 2017 Tax Return, you will need to purchase and download the software for 2017 to prepare your Tax Return and then mail it to the IRS. Here is link to previous years product options: TurboTax Previous Years Products.
