[thrownaway2424]

On the other hand, 1 person with x income pays less income tax than 2 people with 2x income.

[jahewson]

The US has joint filing for married couples so that's not the case, whereas it would be in e.g. the UK.

[quicklyfrozen]

It most certainly is the case in the US... http://en.wikipedia.org/wiki/Marriage_penalty

[Retric]

It's a generally around a 1/2 a % penalty which is swamped by other benefits.

AKA 2 incomes of $87,850 x2 = 175 700 vs extra 879$ in taxes.

At extreme incomes of say 20+M a year or below 18k it's actually far less than 1/2%.

However, there are huge benefits for SS for being a married couple even more so if there is a large income disparity, so on average if they plan ahead Marriage tends to lower taxes. On top of lower expenses which enable better tax avoidance mechanisms.