Tom Cruise and Katie Holmes had one. So did Brad Pitt and Angelina Jolie. Kim Kardashian and Kris Humphries did, too.

The three now-divorced couples all had prenuptial agreements. But prenups are hardly just for Hollywood celebrities.

Any couple who brings personal or business assets to the marriage can benefit from a prenup. The most basic of these contracts lists an inventory of premarital assets that in the event of a divorce will remain the property of their original owner.

“Prenups are good because they preserve the expectations of the parties and prevent surprises in a divorce trial,” says attorney Bob Nachshin, a family attorney in Los Angeles and co-author of “I Do, You Do … But Just Sign Here: A Quick and Easy Guide to Cohabitation, Prenuptial and Postnuptial Agreements.”

“In my (more than 40) years of practice, I’ve never seen a prenuptial agreement that wasn’t enforced by the court,” Nachshin says.

The agreements also can specify that future income from a business or additional assets accrued through inheritance are not to be shared with your spouse if the marriage ends.

“You can basically do anything you want in a prenup, except you can’t limit child support, and you can’t limit child custody and visitation,” Nachshin says.

Yours, mine and ours

Prenuptial agreements can address property acquired before a marriage, such as money in savings, a home or Grandpa’s antique desk, although some states recognize each spouse’s rights to his or her premarital property anyway, according to attorney Brian Liu, co-founder of LegalZoom, an online law center.

“The problem people have is, after they get married, what’s become yours has become co-mingled,” Liu says. “People can’t trace after 10 years of marriage what was theirs and what’s joint property.”

Other areas prenups can cover are the waiving of spousal support and death benefits.

“Even if you make a will and exclude your spouse, some courts will look unfavorably on that,” Liu says. “If you have a prenuptial agreement, you can say, ‘That was my intention, to cut out the spouse.'”

The second time around

Prenups are especially helpful for couples who came into the marriage with children, and for older couples, says Lynne Gold-Bikin, a family law attorney and former chair of the American Bar Association’s family law section.

“Older couples may want to protect children from a prior marriage or protect the ability of the one with lesser assets to go into a nursing home and not give everything over,” Gold-Bikin says.

People who have been married previously are especially aware of the importance of taking these steps the second time around.

“A lot of times, prenuptial agreements have a bad connotation,” Liu says. “I see them happening with people who may have been divorced once, and have children and significant assets, and want to make sure their children and family are protected if something happens.”

I do’s and I don’ts

States impose different rules for prenups. California requires that an agreement be signed at least seven days after it has been presented, that both parties have attorney representation and that all assets should be disclosed.

Those requirements were added to the law after the state Supreme Court upheld former baseball star Barry Bonds’ prenup, despite how it was signed a day before his wedding and without his future wife having legal counsel, says Nachshin, who represented Bonds.

Other circumstances to keep in mind are to never sign such a prenuptial agreement after downing a few alcoholic beverages and to not present a prenup when a woman is pregnant, because her medical condition could lead to the agreement being overturned, Nachshin says.

“Remember to talk about it with your (future) spouse way before you plan your wedding, and have it signed four months before you plan on getting married,” Nachshin says. “Because otherwise, you’re so focused on the prenup that you can’t focus on the joy of marriage.”

Why ‘pre’ is better than ‘post’

Couples who don’t enter into a prenuptial agreement always have the option of forging such a pact after they say their vows. Postnuptial agreements are largely the same as prenups, laying out which assets will remain individual property and which will be shared.

However, states may view postnups differently if they are challenged during a divorce. In California, for example, prenups are presumed to be legally valid, while postnups are presumed to be invalid — meaning the burden of proof is on the spouse seeking to have the terms enforced.

Still, properly executed postnups should stand up to court scrutiny.

“I think if both parties have counsel, and there’s been full disclosure, the postnup will be upheld,” he says.

What’s fair?

Prenuptial agreements are supposed to be based on fair and full disclosure of assets, but states look at this legal tenet in different ways.

The prenup “has to be considered fair at the time it’s enforced,” Gold-Bikin explains.

For example, a spouse may agree he won’t take anything from a business that’s worth $1,000 at the time he and his future wife sign the prenup. But what if she has transformed the business into the next Amazon or sold it for a fat profit by the time they divorce?

Whether it was a “fair agreement” for the husband to not share in the business depends on the state, Gold-Bikin says.

Separate accounts

There are other ways for couples to keep assets separate that can work in conjunction with a prenup, or alone.

A revocable living trust can ensure that certain property or income is directed to someone other than your spouse.

An even simpler tool is to retain separate bank accounts and keep real estate under your own names.

“Some people, when they get married, immediately change (the) title to property so it’s in both their names,” Liu says. “The fact that you put the other spouse on the deed, (a judge) is going to assume you meant to give half of your interest to the spouse as a gift, and is going to consider that joint property.”

What about same-sex couples?

In 2015, the U.S. Supreme Court put same-sex marriage on the same legal footing as other marriages. Therefore, the same prenup rules now to apply to all U.S. couples who are legally married. That means if a same-sex couple creates a prenup when they marry in Illinois and then later move to Texas, the prenup will remain valid.

“As more and more same-sex couples get married, they will experience the same thing as heterosexual couples — they’re going to get divorced,” Gold-Bikin says. “The next time they get married, they will have prenuptial agreements.”