Yes, you can but it’s not a prenup then, you know since it’s not pre, it is post. So you can get a post nup. Many people get a post nup because they didn’t think to get a prenup. They ran out of time to get a prenup. They are now realizing they may need to protect their assets. Or they are heading toward divorce. No matter the reason you can protect your assets after you say “I do” with a post nup.
Now the biggest thing to know about a post nup is that since you are already married most of your “stuff” is probably already community property. So you will be deciding how to divide your martial assets as well anything coming in the future.
So no matter the reason you’re think of getting a post nup, talk to your spouse, decide how you want to divide things, and contact the PreNup Princess.