IHT is charged as a percentage (generally 40%) of the value transferred by a chargeable transfer, subject to exemptions such as transfers to spouses which are not chargeable. Chargeable transfers may be made during a person’s lifetime or on death. As to the former, IHT is charged (at half rates) on the accumulation of the lifetime transfer and chargeable transfers made in the preceding seven years. On death a charge to IHT (at full rates, subject to a taper) arises as if, immediately before that person’s death, he had made a transfer of value equal to the value of his estate immediately before death, together with the cumulative total of chargeable transfers in the preceding seven years. However, in either case, as a form of relief IHT is only levied on the chargeable estate that is in excess of the nil rate band (NRB), which is currently £325,000. In other words, IHT is a two-rate tax, the first being a nil rate of charge on the