What is the marriage penalty?

For the most part, the marriage penalty doesn’t currently exist for most taxpayers. For decades, however, the tax code was written so that married couples who earned a similar amount of income actually had to pay more taxes. In 2003, the tax code was changed, however, to get rid of the marriage penalty. Still, the marriage penalty still does affect couples who each earn $120,000 or more a piece; in that case, filing separately may be more advantageous.