Bank closing balance for jointly account

If you are maintaining proper accounts, then balance will be automatically calculated for each individual.

For example, calculate balance by checking total deposit by each person and total withdrawl for each person.

But in most of cases it may not be practical, if it is not an account for business purpose why to show in balance sheet?

For information purpose if you want to show then show in balance sheet which is bigger or devide proportionaly.

But most accurate method will be to arrive at balance by calculating total deposits and withdrawals of each individual.