Home Tax confusion

CLAPTON

The way I see it is this and maybe I am missing something but...

the 'gain' that is applicable is
220,000 - 180,000 i.e. a total of 40,000
(if fact you can also substract selling costs)

now if you wait until the next tax year the tax payable is 18% i.e. 7,200 .
However your sister has CGT allowance of 9,200 so no tax will be payable assuming she will have no othe CGs next year.
Even based on this years CGT law the amount payable isn't very much once you substract selling costs.