Okay, if you want to make your life easier, just add the spouse to your existing account. The fact that you were married in September makes you married for all of 2016. The IRS looks at the last day of the year to determine if an individual was married or not. As a married individual you may file as married filing jointly, (MFJ) or married filing separately, (MFS). MFJ results in more favorable income tax treatment including lower tax rates, more deductions and credits.