Additional duty on information technology imports imposes an ad valorem levy on specified zero-duty goods at import. An additional ad valorem duty of four per cent is directed to apply to specified information technology goods that otherwise attract zero per cent basic customs duty when imported into India, exercised under sub section (5) of section 3 of the Customs Tariff Act, 1975, and made applicable to goods specified in earlier notifications including notification Nos. 25/98, 25/99, specified entries of 21/2002, and notification Nos. 21/2005, 24/2005 and 25/2005.