This section and sections 127 to 129 apply where a building that is a dwelling ("the old dwelling") is demolished after 1 April 2013.
Except so far as express provision to the contrary is made in sections 127 to 129, any question as to whether a person has a single-dwelling interest in the dwelling, and any question as to the taxable value of such an interest, is determined as if the dwelling had not been demolished.
For the purposes of subsection (1) the demolition of a building is treated as having occurred after 1 April 2013 if a day after 1 April 2013 is the first day on which—
the demolition has begun, and
as a result, the building is no longer suitable for use as a dwelling.
In this section "building" includes a part of a building.