You have two choices. You can file an Amended return and report the Form 1099-DIV and pay any additional tax; or, you can wait for the IRS realize you didn't include the 1099-DIV on your tax return. for the later, the IRS will propose a change to your tax return and bill you for any additional tax plus any applicable penalty and interest. If the amount of the dividend is small, I would wait for the IRS.
