<s>[INST] What is tax on regular assessment and how is it paid? [/INST] Under the Income-tax Act, every person has the responsibility to correctly compute and pay his due taxes. Where the Department finds that there has been understatement of income and resultant tax due, it takes measures to compute the actual tax amount that ought to have been paid. This demand raised on the person is called as Tax on regular assessment. The tax on regular assessment-400 has to be paid within 30 days of receipt of the notice of demand . </s>