law: Negotiable Instruments Act, 1881 
  80. Interest when no rate specified 
  When no rate of interest is specified in the instrument,
  
  interest on the amount due thereon shall, 23[notwithstanding any agreement
  
  relating to interest between any parties to the instrument], be calculated at
  
  the rate of 24[eighteen per centum] per annum, from the date at which the same
  
  ought to have been paid by the party charged, until tender or realization of
  
  the amount due thereon, or until such date after the institution of a suit to
  
  recover such amount as the court directs.
  Explanation:  When the party charged is the indorser of an
  
  instrument dishonored by non-payment, he is liable to pay interest only from
  
  the time that he receives notice of the dishonor.