Postnuptial contract – in many legal systems this is the synonym of the marriage agreement, which regulates the financial relations between the spouses for the term of the marriage (incl. who will hold debts, etc.), and after its dissolvement. (i.e. dealing with post-marital assets). It is similar to the prenuptial agreement, but it is concluded before entering in marriage.
*Note that it is advisable to hire a lawyer who to draw your contract. Lawyers are qualified in Law and they know what terms and conditions should be implemented in such forms to protect your interests; as well to consult you on the clauses of proposed agreements to you for signing.