While a prenuptial agreement is generally preferable to a postnuptial agreement in terms of the strength of the protection it offers, postnuptial agreements are useful and enforceable if they remain within the scope of what they can actually protect. Prenuptial agreements offer far greater protections, but a postnuptial agreement that is carefully researched and constructed may provide significant protections in the right circumstances.
Postnuptial agreements may protect certain kinds of property from property division in divorce, but only within relatively tight constraints. If, for instance, one spouse purchases a car that he or she is very fond of, the couple may mutually agree to separate it out as that spouse's property and leave it off the property division table if divorce comes knocking. This is also useful to those who own businesses and do not wish to see the success of the business dependent on the success of the marriage.
However, postnuptial agreements have many fewer protections available, and cannot usually protect one spouse's property from the other spouse's debt as easily as a prenuptial agreement can. Similarly, a postnuptial agreement that seeks to introduce rules of conduct into a marriage is not likely to stand up in court.
If you and your spouse are considering a postnuptial agreement, it is important to understand what your true motives are, and whether or not a postnuptial agreement is truly the best fit for your needs. Personalized guidance from an experienced family law attorney can help you look at these issues carefully and identify strategies you can use to protect your property and your marriage efficiently.
Source: FindLaw, "The Enforceability of Postnuptial Agreements: Massachusetts Weighs In, Part Two in a Two-Part Series of Columns on Postnuptial Agreements," accessed March 23, 2018