Subsection (4) below applies where—
a gain to which section 222 applies accrues to an individual on the disposal of, or of an interest in, a dwelling-house or part of a dwelling-house,
the time at which the dwelling-house or the part of the dwelling-house first became the individual's only or main residence ("the moving-in time") was within the first 24 months of the individual's period of ownership,
at no time during the period beginning with the individual's period of ownership and ending with the moving-in time was the dwelling-house or the part of the dwelling-house another person's residence, and
during the period beginning with the individual's period of ownership and ending with the moving-in time a qualifying event occurred.
The following are qualifying events—
the completion of the construction, renovation, redecoration or alteration of the dwelling-house or the part of the dwelling-house mentioned in subsection (1);
the disposal by the individual of, or of an interest in, any other dwelling-house or part of a dwelling-house that immediately before the disposal was the individual's only or main residence.
In determining whether and, if so, when a qualifying event within subsection (2)(b) occurred, ignore section 28 (time of disposal where asset disposed of under contract).
For the purposes of subsections (1) and (2) of section 223, as they have effect in relation to the gain, the dwelling-house or the part of the dwelling-house mentioned in subsection (1) above is to be treated as having been the individual's only or main residence from the beginning of the individual's period of ownership until the moving-in time.