You are entitled to half of the amount of money that your spouse put into the account during the marriage. The balance of the account prior to your marriage date is your spouse's separate property, not subject to division.
For example, if your spouse has an account with a present value of $100,000 and $20,000 of the account was contributed during the marriage, then you are entitled to half of $20,000 (i.e., $10,000) and $80,000 is your spouse's separate property, not subject to division.
This is a general answer. You need to consult a Family Law attorney who understands the process of dividing marital property, requesting spousal support, and all attendant issues that arise in a divorce, in order to get an answer specific to the facts of your case.
The foregoing does not establish an attorney client relationship with Attorney Stephen D. Gregg. The information given in Attorney Stephen D. Gregg's answer is not legal advice and is only given for educational purposes.
Attorney Gregg is correct, in general marital assets (a pension) is divided 50/50. That means the portion of the retirement account that came into existence from the date you got married until the ending date, is marital and subject to 50/50 division. Many other aspects such as other debts and assets may also play a big issue in how one ultimately accounts for the division.
I suggest you seek a consultation with an attorney. You will want to discuss your overall debts, assets, communication ability, children if there are any, current concerns if any on incurring additional debt or depleting assets. The consultation fee is well worth the information and guidance that you receive.
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