law: Delhi Rent Control Act, 1958 
  7. Lawful increase of standard rent in certain
  
  cases and recovery of other charges. -
  (1) Where a landlord has at any time, before
  
  the commencement of this Act with or without the approval of the tenant or
  
  after the commencement of this Act with the written approval of the tenant or
  
  of the Controller, incurred expenditure for any improvement, addition or
  
  structural alteration in the premises, not being expenditure on decoration or
  
  tenantable repairs necessary or usual for such premises, and the cost of the
  
  improvement, addition or alteration has not been taken into account in
  
  determining the rent of the premises, the landlord may lawfully increase the
  
  standard rent per year by an amount not exceeding [(Subs. by Act 57 of 1988,
  
  sec.3, for "seven and one-half per cent." ( w.e.f .
  
  1-12-1988) ten per cent.] of such cost.
  (2) Where a landlord pays in respect of the
  
  premises any charge for electricity or water consumed in the premises or any
  
  other charge levied by a local authority having jurisdiction in the area which
  
  is ordinarily payable by the tenant, he may recover from the tenant the amount
  
  so paid by him; but the landlord shall not recover from the tenant whether by
  
  means of an increase in rent or otherwise the amount of any tax on building or
  
  land imposed in respect of the premises occupied by the tenant:
  Provided that nothing in this sub-section shall
  
  affect the liability of any tenant under an agreement entered into before the 1st of January 1952 , whether express or
  
  implied, to pay from time to time the amount of any such tax as aforesaid.