HMRC have also published detailed guidance note on the vexed question of repairs, renewals and improvements and their treatment for tax purposes: HMRC Brief 5/2013. It covers a wide variety of circumstances explaining what is meant by a repair and where elements of improvement will cause expenditure not to be categorised as a repair but as a new asset, possibly (but not always) qualifying for capital allowances.

The old arguments about what is a repair and what is a replacement of the entirety are all discussed, including the use of different materials and the effect of changing technology. Of course there will always be areas of controversy and uncertainty, but this is a very useful document.