A prenuptial or premarital agreement is a contract entered into by two people prior to a marriage or civil union. The content of a prenuptial agreement can vary widely, but commonly includes provisions for the division of property should the couple divorce and any rights to spousal support during or after the dissolution of marriage. In the United States, prenuptial agreements are recognized in all fifty states and the District of Columbia.

In most jurisdictions, five elements are required for a valid prenuptial agreement:
- Agreement must be in writing (oral prenups are never allowed)
- Must be done voluntarily
- Full and/or fair disclosure at the time of execution
- The agreement cannot be unconscionable
- It must be executed by both parties (not their attorneys) "in an acknowledgment (law), before a notary public

You should consider having a prenuptial agreement if:
- You have assets such as a home, stock or retirement funds 
- You own all or part of a business 
- You may be receiving an inheritance 
- You have children and/or grandchildren from a previous marriage 
- One of you is much wealthier than the other 
- One of you will be supporting the other through college 
- You have loved ones who need to be taken care of, such as elderly parents
- You have or are pursuing a degree or license in a potentially lucrative profession such as medicine 
- You see a big increase in income because your business is taking off

What you CAN do with a prenuptial agreement:

- Keep finances separate: Every state has laws designating certain kinds of assets accumulated during a marriage as marital property or community property, even if these assets are held in the name of only one spouse. If a couple divorces, or when one spouse dies, the marital or community property will be divided between them, either by agreement or by a court. If you want to avoid having some or all of your individual accumulations during marriage divided up by a court, you can do so with a premarital agreement.

- Protect your spouse from debts: You might bring debts, as well as assets, to a marriage. If there is no prenup, creditors can sometimes turn to marital or community property to satisfy the debts of a spouse. But if you want to make sure that you do not owe money, you can use a prenup to limit your liability for each other's debts.

- Provide for children from previous marriages: A prenup is helpful if either spouse has children from another relationship and you want to make sure that your children inherit their share of your property. In a prenup, one or both spouses can give up the right to claim a share of the other's property at death, perhaps in exchange for an agreed upon amount of property.

- Keep property in the family: If your property includes something you want to keep in your birth family, whether it be an heirloom or a share in a family business, you and your spouse can agree that it will remain in your family, and you can specify that item in your prenup. This can even include property that you expect to receive in a future inheritance.

- Follow through by making your estate plan: In addition to using your prenup to waive inheritance rights and state your intentions for passing on your property at death, it is very important that you prepare the estate planning documents - a will, living trust, etc. - that actually transfer your property as you intend.

- Define who gets what if you divorce: Without a prenup, state law will specify how your property will be divided should you ever divorce and the result of those laws might not be desirable. However, you can use a prenup to establish your own rules for property division and avoid potential disagreements in the event of a divorce. In most states, you can also make agreements about whether or not one or both of you will be entitled to alimony. Some states forbid or restrict agreements about alimony, however.

What you can NOT do with a prenuptial agreement:

- Restrict child support, custody, or visitation rights: No state will honor agreements limiting or giving up future child support., custody or visitation rights. This is because state lawmakers consider the welfare of children to be a matter of public policy and do not enforce any private agreements that would impair a child's right to be supported or to have a relationship with a parent in the future.

- Give up the right to alimony, in a few states: A few states limit your ability to give up your right to alimony  (also called spousal support or seperate maintenance) in the event of a divorce. Other states allow these waivers, so you will need to know what your state laws say if you are considering this kind of agreement.

- Encourage divorce: At one time, courts viewed any prenup specifying how things would be divided up in case the couple splits as void and unenforceable because they believed it promoted divorce. Today these agreements are allowed, but judges in some states still do not favor them. If the agreement appears to offer a financial incentive for divorce to one party, it may be set aside.

- Make rules about nonfinancial matters: For practical reasons, you should keep personal agreements out of your prenup. These kinds of nonmonetary agreements aren't binding in court, and in fact they could cause a judge to take your entire prenup less seriously.

Examples of nonfinancial matters that sometimes make their way into a prenup are: responsibility for household chores, use of last names after you marry, agreements about having and raising children, how you will relate to in-laws or stepchildren, and whether you will have any pets and who will be responsible for them.

Some examples of other matters people include in their prenuptial agreements:

- Whether to file joint or separate income tax returns or to allocate income and tax deductions on separate tax returns

- Who will pay the household bills and how

- Whether to have joint bank accounts and, if so, how you will manage them

- Agreements about specific purchases or projects, such as buying a house together or starting up a business

- How you will handle credit card charges (whether you will use different cards for different types of purchases, what kinds of records you will keep,how you will make payments, etc.)

- Agreements to set aside money for savings

- Agreements for putting each other through college or professional school

- Whether you will provide for a surviving spouse (in your estate plan, with life insurance coverage, etc.)