Typically, inheritance money is considered to be separate property whether it was acquired before or during the marriage. However, inheritance may be considered martial property if it was comingled. For instance, if the money was put into a joint account or used to improve a marital residence, that money is now considered marital property. This is generally true whether the money was intended to be shared with a spouse.
A judge may rule that a portion of the inheritance remains separate property regardless of whether it was comingled. In this scenario, the burden of proof would be on the person asserting that the money was not intended to be shared. To avoid this issue, it may be worthwhile to have a prenuptial agreement. A valid agreement may allow the two parties to determine what happens to any money that is inherited during the marriage.
In any divorce when property division is being disputed, it may be worthwhile to seek the advice of a family law attorney. An attorney may be able to help figure out which assets are separate and which are considered marital. It may also be possible for an attorney to help find assets that one party might be attempting to shield from division.
If a couple has a prenuptial agreement an attorney may be able to review that agreement to ensure that it complies with state law. If it does not or if one party has violated one or more clauses within the agreement, it may be possible to have it invalidated in court. That may lead to the couple agreeing to a new settlement out of court or having a judge make the final ruling.
Source: Findlaw, "Inheritance and Divorce", December 01, 2014