Inheritance Tax is a tax on the estate (the property, money and possessions) of someone who’s died. A UK domiciled individual is liable to inheritance tax on his worldwide assets. Individual's who are not domiciled in the UK, are only liable to inheritance tax on assets situated in the UK
You can find guidance on how to value an estate below, which includes a calculator to help work out of inheritance tax is payable.
How Inheritance Tax works: thresholds, rules and allowances