In many places, you don't. Washington State all property is 50/50. Half my income is my wife's, even though I make 800k and she makes nothing.
I dunno, the idea that you are willing to make a commitment to someone for the rest of your life but also try to hold back money from them is so alien.
My rationale is that prenups are an acknowledgment that sometimes, people discover things don’t work out. Agreeing what each person has from the beginning confirms the commitment of marriage is beyond the money/wealth that existed before.
I’ve never been married yet but this perspective seems rare. So many people’s lives get destroyed or seriously damaged after a bad divorce. Why not do something that would ease the pain for both parties?
The alternative is to say, "knowing who we are now, we are going in together. Fifty fifty. Egalitarian. If someday in the future we split, we both walk away with half."
Holding on to the idea that somehow anything is "mine" or "yours" rather than "ours" is a waste, imo. You can try and protect "mine" with a prenup, or you can accept the "ours" nature and make peace with that. I find the latter to be simpler, more elegant.
Even though Washington is a community property state, you can still have a prenup agreeing that your two incomes will be separate property, if you so wish and if you execute it correctly.
In the states I'm familiar with, that's largely just gonna cover pre-existing assets, and you need to be talking about a large initial discrepancy (millions or more) probably to make it worthwhile. I've also been advised that it's easier to do something more like "the prenup will say you'd get 10%, but you revoke your claim to trying to get more" than some sort of "it's all mine!!" - it needs to be non-coercive and give both parties consideration and a reason to make the agreement. Lawyers told me that there's a often a big difference in that world between "what a lawyer might be willing to write up and get people to sign" and "what's gonna hold up in court."
