Couples who are separated, whether informally or legally, are still married in the eyes of the law, regardless of how independent their lives have become. This means that if either spouse has a sexual relationship with another person during the separation period, they have probably committed adultery.

Can I file single on my taxes if I am married but separated?

If youre legally separated – and not all states recognize this concept – you can file as a single taxpayer even if youre not divorced by December 31. In this case, the IRS accepts your decree of separation as sufficient proof that your marriage has ended.