(3)Any instalment of betterment contribution or part thereof which remains unpaid on the expiry of the period under sub-section (2) shall with effect from the date of which such period expires, carry interest at the rate of 6 per cent per annum :Provided that when the recovery of any instalment is postponed under Section 58-1, such instalments shall not be deemed to be remaining unpaid for the purpose of this sub-section during which the recovery thereof remains postponed.
