As per provisions of income tax act. A person is liable to pay income tax on his income if above basic exemption limit. There are 5 heading under which income of a person can be categorized:

1. Salary
2. Income from House property
3. Capital Gains
4. Income from business and profession
5. Other Income.

There is difference rules for calculation of total income of a person from different sources. Hence please note that “Income” is liable to tax but “Gross receipts” are not subject to tax. Bank balance are also not subject to tax.
Now coming to your question, “Closing bank balance” is not directly liable to tax and You are not required to pay any tax on your closing bank balance. But your bank statement may be used to calculate your income and then to assess your tax liability.
If assessee is doing any business and doing all his receipts and payment through a bank account. Still closing bank balance cannot be treated his income and He is not required to pay income tax on his closing bank balance. But his bank statement may be used to arrive at his total income and his income may be higher or lesser than the closing bank balance, And he is liable to pay income tax on his income.
Why closing bank balance is not his income:

• Payment made from bank account may be more than the allowed limit of expenses.
• Receipts in bank account may not have income nature but it may be loan or advances.
• All payment from bank account are not necessarily be allowed expenses but may be repayment of loans or advances.
• Some income may be accrued income which are not yet received hence not reflected by bank statement.
• Some expenses may be outstanding expenses which are not yet paid.
• many more…..

Hence No tax applicable on closing bank balance but bank statement may be used to arrive at your income.
AND

• Income tax is liable to be paid on Total income.
• Income tax is not liable to be paid on Gross receipts.
• Income tax is not liable to be paid on bank balances.