Increase in rent on account of payment of rates, etc., excepted

Where a landlord is required to pay to a local authority in respect of any premises any rate, cess or tax imposed or levied for the purposes of such authority, he shall be entitled to make an increase in the rent of the premises by an amount not exceeding the increase paid by him [by way of such rate, cess or tax over the amount paid] in the period of assessment which included the date of the coming into operation of this Act, [or the date on which the premises were first let, whichever is later,] and such increase in rent shall not be deemed to be an increase for the purposes of section 7.