How do I value accounts that change in value regularly, like bank accounts?

While larger bank accounts and cash equivalents can be added to the balance sheet and offset with other assets, operating accounts can be harder to divide because the values fluctuate regularly. It is common to pick a date to divide the balance in an operating account that matches up with all expenses being paid and before income is received.  An end of month date may be a good time to divide all balances in accounts that fluctuate greatly to keep things fair and avoid confusion.