If you want your prenup to be fair, it should mimic the laws in your state. For example, if you owned your home before marrying and if you and your spouse live in it during your marriage, you should not ask her to contribute financially to mortgage payments, taxes, upkeep or repair. If she paid any of these things without a prenup, the law would give her a stake in your home. You can use a prenup to declare that if you divorce, you and your spouse agree that your home is not marital property and subject to property distribution. However, it would not be fair to ask her to contribute toward your sole investment in spite of that. You can arrange your budget so her income pays for utilities and other such household expenses while you handle the actual costs of paying for and maintaining the house.
A prenuptial agreement can also protect your children from a previous marriage in the event of your death. You can use both a prenup and your will to state that anything you owned before you got married should go to your children. Your spouse can waive any right to that property in a prenup so there's no confusion about what the two of you intended. If you die without a will, depending on the probate laws in your area, your spouse might conceivably inherit half of everything you own. Your children from a previous marriage would receive only 50 percent of your premarital property's value. Having both a will and a prenup can prevent this. However, in many states, if your will leaves your spouse very little, and you’re more generous in your prenup, the prenuptial agreement would supersede your will and prevail.
If you’re very concerned about keeping your premarital property separate so it can only pass to your children when you die, you can also protect it by placing it in a revocable living trust and naming your children as the beneficiaries. This takes it out of your estate so it can pass directly to them without going through probate. For optimum fairness, you should mention the trust in your prenup so your spouse is aware of the situation. Most state laws will only uphold a prenuptial agreement if both spouses have made full disclosure regarding their assets.
Most states have laws to prevent prenuptial agreements from imposing an unfair burden on either spouse. If you propose something in your prenup that is grossly unfair, it’s possible that a court will not honor it. Some states mandate a waiting period between the time you give your spouse a prenup to sign and the date she does so. This guarantees that she has ample time to digest its terms and to be sure she agrees with them. If she’s pregnant at the time she signs it, some states may declare the agreement to be invalid. Some jurisdictional laws require that both spouses give the prenup to independent attorneys to review for fairness.