No, for taxes, married filing separately is a different category than single. Married filing separately results in a higher tax bill than married filing jointly for most couples.

There are places in the tax code where Single != Married Filing Separately.

One pertinent example is that Washington State's capital gains tax applies after $270k per single person, per married couple filing jointly OR split in half for married filing separately. Which could be a theoretical $18.9k/year difference in taxes.

Yeah, that particular deduction reeks of some big brain energy. My family is going to be outta here by the end of the year, hopefully.

Married filed separately effectively locks you out of a lot of benefits when compared to unmarried filing single, or married filing jointly.

Nope. It's a reason some might note get married.