How Is Wife's Share of Accrued Savings Determined?

A spouse is entitled top half the community contributions to an account plus any increase in the value of those contributions due to interest and/or appreciation in value (if a stock account or similar holding), less any monies withdrawn from the account to make community purchases or pay community debt. The problem from your point of view is that monies contributed during the marriage are presumptively community, and you would have the burden of tracing the individual contributions and withdrawals to establish what portion of the account was separate. If you can't even say how much was in the account when you got married, that would seem an impossible task, at least without bank records.

First you can get records from your bank and you should. Second you need a financial who specializes in computing the community property interest in an account. A family law attorney in your county can make a good recommendation.

If you can't prove your separate property claim. then she gets half of the whole account. The court presumes its community and you alone bear the burden of proving otherwise.

You have it right and the bank can give you records to show what the bank balance was on the date of marriage.