Your spouse’s will can never be less generous than the conditions of the prenuptial agreement. However, a will can always leave more than the amount agreed upon in the prenup.
You can include a sunset clause in your prenuptial, which means the agreement will only be valid for a predetermined amount of time. You can decide the prenup will expire in ten years, twenty, or at any other time you select. This option allows people the comfort of a prenuptial while not feeling bound by it after the marriage has proven to last.
While it may seem obvious, make sure the agreement is in writing. Also have witnesses present when it is signed. The contract should be signed in triplicate. One copy should go to the groom, another to the bride, and a third should be kept with a third party or in a safety deposit box.