If your return is accepted by the IRS, you must amend your return to change it to married filing jointly and include all of your spouse's information. Do not make any changes on your tax return until it is processed by the IRS and you receive your refund if you are getting one. You can then start your amended return form 1040X. The form is estimated to be available in TurboTax on 2/7/19. The amended return must be printed, signed, and mailed. It can't be efiled. Your spouse must not file a tax return by himself.