Ahh, the same applies when you’re getting divorced. If the divorce papers say you separated from your spouse on Dec. 31, 2020, you can not file as “married” for the 2020 tax year, even if you actually were married (almost) the entire year. Now you may wonder what happens when you have a child before or on Dec. 31…
Well, short and concise, you can claim your child as a dependent for the entire year, but you need a Social Security number to do that. If you forgot to claim her/him as a dependent, you should be able to file Form 4868 in order to extend your filing deadline, but before you do so, it’s best to pay any taxes due.