(1)Except where this Act otherwise provides, the rateable value on any day of a dwelling-house shall be ascertained for the purposes of this Act as follows:—
(a)if the dwelling-house comprises lands and heritages for which a rateable value is then shown on the valuation roll, it shall be that rateable value;
(b)if the dwelling-house forms part only of such lands and heritages, its rateable value shall be taken to be such value as is found by a proper apportionment of the rateable value so shown.
(2)Any question arising under this section as to the proper apportionment of any value shall be determined by the sheriff, and the decision of the sheriff shall be final.
(3)In this Act “the appropriate day”,—
(a)in relation to any dwelling-house which, on 23rd March 1965, comprised or formed part of land and heritages for which a rateable value was shown on the valuation roll then in force, means that date;
(b)in relation to any dwelling-house of which a tenancy granted before 1st December 1980 becomes, or would but for its low rent become, a protected tenancy by virtue of section 4(3) above, means 1st December 1980; and
(c)in relation to any other dwelling-house means the date on which a rateable value is or was first shown on the valuation roll.
(4)Where, after the date which is the appropriate day in relation to any dwelling-house, the valuation roll is altered so as to vary the rateable value of the lands and heritages of which the dwelling-house consists or forms part and the alteration has effect from a date not later than the appropriate day, the ratable value of the dwelling-house on the appropriate day shall be ascertained as if the value shown on the valuation roll on the appropriate day had been the value shown on the roll as altered.
(5)The preceding provisions of this section apply in relation to any other land as they apply in relation to a dwelling-house.