When any sum is payable as a result of any order passed under the Act, then the Assessing Officer shall serve upon the assessee a notice of demand U/s 156 specifying the sum so payable.
Whereas Section 143 (1) is itself deemed as notice of demand & demand notice U/s 156 need not to be attached with notice U/s 143 (1).
If the amount specified in any notice of demand under section 156 is not paid within 30 days of the service of notice, then he shall be deemed to be an ASSEESSEE IN DEFAULT for the amount remaining unpaid. The assessee shall be liable to pay simple interest U/s 220 at one and one-fourth per cent for every month or part of a month comprised in the period commencing from the day immediately following the end of the period mentioned in sub-section (1) and ending with the day on which the amount is paid. In addition to interest U/s 220, he shall be liable to pay a penalty U/s 221 which the Assessing Officer may levy. However such penalty shall not exceed the amount in arrears.
As per the Finance Act, 2012 Section 201 (1) shall apply if assessee does not deduct whole or part of TDS. Also this section applies where assessee after deducting TDS fails to pay the whole or part of TDS. Section 201 (1) shall not apply if there is a delay in deduction or delay in payment of TDS.
Provided that any person who fails to deduct the whole or any part of the tax in accordance with the provisions of this Chapter on the sum paid/credited to a resident shall not be deemed to be an assessee in default in respect of such tax if such resident-
and the person furnishes a certificate to this effect from an accountant in such form as may be prescribed.
The Finance Act, 2012 also clarifies that interest U/s 201 (1A) shall not be levied where section 201 (1) applies.