IHTM28100 - Investigating liabilities: overseas taxes
Special rules (IHTM27181) apply to overseas taxes that are similar in nature to Inheritance Tax (IHT). These may in some cases be set against the IHT liability.
For other types of overseas taxes the general rule is that they can normally only be deducted from the value of property in the country that imposes the tax. This is because the taxes are unenforceable in other countries, Government of India v Taylor  AC 491.
There are three exceptions to this rule: