Under the current rules, no IHT is charged on the first £325,000 of your estate, and this can be increased to £625,000 for married couples. Above this amount, anything you leave behind is taxed at 40% (or 36% if you choose to leave more than 10% of your wealth to charity).
Under new rules being phased in from 2017 (the ‘main residence’ allowance), you can pass on your main residence to their children, stepchildren or grandchildren to further increase the nil IHT band. By 2020 this will mean that if you own a property worth up to £1million you’ll be able to leave it to your dependants completely free of IHT.