For the vast majority of married taxpayers, filing jointly is almost always the best option, but there are times when one spouse may wish to file a separate return. In this case, they will have to use the “married filing separately” filing status. Unfortunately, this is by far the least advantageous filing status in the tax code, and it is usually reserved for extenuating circumstances — perhaps the couple is separating and no longer wants to share finances, or maybe one spouse is committing some form of tax fraud, and the other wants nothing to do with it.