Death and Personal Representatives: Variation of the devolution of an estate: Instruments of variation: Variations: instruments of variation: general
A person who executes an instrument of variation in relation to a will or intestacy provisions gives up his or her right to receive assets or interests or a share of the residue that he or she would otherwise have received. In addition the person gives directions as to how the assets etc. involved shall devolve following the variation. If the estate is governed by a will the instrument does this by deeming certain clauses to have been removed from the will and certain other clauses to have been inserted in their place. For intestacies it does it by deeming assets to pass under a will having clauses containing the new conditions. Strictly speaking however the instrument of variation does not actually vary the will itself, but only the effects of the will. Therefore it does not have retrospective effect as regards third parties, e.g. HMRC, except to the extent that statute, TCGA92/S62 or IHTA84/S142 so provides.
Simple guidance can be found on Inheritance Tax on the GOV.UK Internet site.
Although in many cases a deed may be necessary to achieve the desired legal effect in England, Wales and Northern Ireland, because of the absence of consideration in most cases, the relevant legislation uses the word ‘instrument in writing’.
An instrument of variation may be executed even if the assets involved have already vested in the legatee. But if the assets have been sold by the legatee before the instrument is executed, there would appear to be difficulties in accepting the instrument’s validity as an instrument of variation, on the basis that in general law the instrument takes effect from the date of execution, and no one can make a gift of property which he or she does not have. So what the person executing the instrument can do is to make a gift of cash, not the asset which is no longer owned. See further the Special Commissioner’s decision in Soutter’s Executry v CIR,  STC(SCD)385, an IHT case.