(1)In this Chapter “wasting asset” means an asset with a predictable life not exceeding 50 years but so that—
(a)freehold land shall not be a wasting asset whatever its nature, and whatever the nature of the buildings or works on it;
(b)“life”, in relation to any tangible movable property, means useful life, having regard to the purpose for which the tangible assets were acquired or provided by the person making the disposal;
(c)plant and machinery shall in every case be regarded as having a predictable life of less than 50 years, and in estimating that life it shall be assumed that its life will end when it is finally put out of use as being unfit for further use, and that it is going to be used in the normal manner and to the normal extent and is going to be so used throughout its life as so estimated;
(d)a life interest in settled property shall not be a wasting asset until the predictable expectation of life of the life tenant is 50 years or less, and the predictable life of life interests in settled property and of annuities shall be ascertained from actuarial tables approved by the Board.
(2)In this Chapter “the residual or scrap value”, in relation to a wasting asset, means the predictable value, if any, which the wasting asset will have at the end of its predictable life as estimated in accordance with this section.
(3)The question what is the predictable life of an asset, and the question what is its predictable residual or scrap value at the end of that life, if any, shall, so far as those questions are not immediately answered by the nature of the asset, be taken, in relation to any disposal of the asset, as they were known or ascertainable at the time when the asset was acquired or provided by the person making the disposal.