If all the money in the account is from wages, then I usually apply CCP Sect. 704.070 in the amount of 75% of the account balance, and also Sect. 706.051 for the remaining 25%. I have never had any problem with that approach.
There is no exemption for money in your bank account except the so-called "wildcard" exemption. $400 is something the trustee would not bother with. Why don't you spend or withdraw the money before you file? You should not attempt to file your BK without a lawyer's assistance. Too many things can go wrong.
Put the $400 toward legal and filing fees.
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