In most states marital property is defined as acquisition during the marriage and not during the co-habitation, though the length of time of separation may be a factor in determining the equities of the distribution. You should check with a Pennsylvania attorney.
In Pennsylvania, a retirement plan such as a 401K is generally valued from the date of marriage to the date of separation. However, gains on the premarital portion are also considered marital property. In addition, gains on the marital portion accrued after separation will be considered marital property. Depending on the value of the account, it is usually best to have an expert value the marital portion. Because retirement plans usually contain stocks and bonds that gain and lose value over the years, this can be a complex calculation. However, your attorney should know experts who can perform this analysis for a reasonable price. A retirement plan usually must be divided be court order so that neither party incurs tax consequences or early withdrawal fees. You should be able to find out what your plan requires from the plan administrator.
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