Why can't I.....?

[KatyMac]

put the costs of my extension through as an expense on my Self Assessment?

because you personally benefit from the increased value of your house?

I suppose tho' an estate agent has said that it will reduce the value of the house - cos who wants a 2 bedroom house with a 42 ft conservatory

It's only used for childminding....and occasionally as a practice roo for dh's dancing

Why can't you at least put some of it through? Can you consult an accountant?

Apparently I can put the furniture through and the blinds - but not the floor tiles or the underfloor heating

or the walls or the roof

Doesn't this mean the house will come under CGT ruling when sold?

Because under taxation rules it is a capital item and not a revenue item.

Only revenue items can be put through as an expense.