What Are the Inheritance Threshold Rules and Allowances in the United Kingdom? Inheritance Tax (IHT) is a tax on the estate (the property, money, and possessions) of a deceased person. In the United Kingdom, there are rules and allowances for inheritance tax that determine how much tax an individual or their estate will have to pay. Visit - https://www.probatesonline.co.uk/how-does-inheritance-tax-taper-relief-work-in-the-united-kingdom/