[tzs]

The US tax code also rewards people getting married, typically when the partners have very different incomes (see marriage bonus).

Marriage penalties and bonuses are a consequence of joint filing combined with a progressive rate structure. They continue to exist because to get rid of them would require giving up either join filing or progressive rates, and it is very unlikely that people would go for giving up one or both of those.

[oneshot908]

So what you're saying is that the US tax code continues to reward one partner sacrificing their career and penalizes partners who wish to both continue their careers?

There's more than one way to make ends meet and I'd be happy to see the wide variety of elaborate tax breaks available to high-income sorts based on elaborate business constructs removed to make up for this rather than punish young married couples. But then, I'm all for a mostly flat tax, warts and all, no deductions whatsoever, past a certain level of income, say the national median.