Premarital agreements: Marriage is the consideration. If no marriage, then no enforcement. SoL is three years.
Separation agreements: can define property division, spousal support, child support, custody, and visitation. May be merged into divorce decree if they are based on full and fair disclosure and consent of the parties. Must be in writing, executed by the parties, and notarized.
Property Settlement agreements: entered into BEFORE a divorce decree is issued.