A postnuptial agreement allows a married couple to protect themselves and their assets in the case of a future divorce.

Arthur D. Ettinger, partner and chair of Greenspoon Marder's New York Matrimonial and Family Law division, said postnuptial agreements are growing more popular.

Both documents have similar objectives. A postnuptial agreement can be harsher and more practical than a prenup, says Washington, D.C. attorney Joel W. Anders.

Peter Mott, partner at Twomey, Latham, Shea, Kelley, Dubin & Quartararo in New York, says a postnuptial arrangement varies legally from a prenuptial agreement.

"The consideration of the prenuptial agreement is the impending marriage. If you never get married, the prenuptial agreement is meaningless," Mott says.

Postnuptial agreements are useful. Marriage problems are a common reason to acquire a postnuptial agreement.

The agreement usually covers each spouse's assets, alimony and maintenance expectations, and legal fees and child support.

Prospective clients should give their attorney a list of their assets and discuss aims and concerns.