A postnuptial agreement is an agreement that in is entered into after the parties are married and is usually contemplated and entered into when spouses are going through hard times and considering either divorcing or reconciling but want to ensure that in the event their reconciliation is unsuccessful that they have an agreement in place to avoid potentially costly divorce litigation.  A valid postnuptial agreement generally requires that the spouses provide each other with full financial disclosure of all of their assets and the reasonable values thereof, liabilities and the amounts thereof, income and net worth and usually (but not always) need to provide reasonable and fair provisions for both parties.  Such agreements can, and often do, serve the salient purpose avoiding costly and time consuming divorce litigation when and if one of the spouses does in fact subsequently file for divorce.