You may file an amended return at any time once your original has been submitted and accepted. If the corrected DIV doesn't change your refund/tax due, however, it is not necessary to amend your tax return. So please start the amendment and see if the form changes your tax return at all... if not, you are not required to amend.
Please note that the amendment must be printed and mailed, it is not submitted electronically. If your return has been submitted- please wait - if it's rejected for some reason, you can add your 1099-div and re-send the return. If your return has been submitted and accepted- you will have to amend; the return is mailed; takes about 16 weeks to process. Here are amending instructions.
