For the purposes of section 22, the annual value of any property shall be deemed to be—
[a] the sum for which the property might reasonably be expected to let from year to year; or
[b] where the property or any part of the property is let and the actual rent received or receivable by the owner in respect thereof is in excess of the sum referred to in clause [a], the amount so received or receivable; or
[c] where the property or any part of the property is let and was vacant during the whole or any part of the previous year and owing to such vacancy the actual rent received or receivable by the owner in respect thereof is less than the sum referred to in clause [a], the amount so received or receivable :
Provided that the taxes levied by any local authority in respect of the property shall be deducted [irrespective of the previous year in which the liability to pay such taxes was incurred by the owner according to the method of accounting regularly employed by him] in determining the annual value of the property of that previous year in which such taxes are actually paid by him.