IHT treaty gap: why most countries have no bilateral estate tax treaty
Knowledge Article · Inheritance & Estate Planning
The treaty gap: why double taxation is the default, not the exception
When people discover they face inheritance tax in two countries, the instinctive question is “is there a treaty?” For income tax, the answer is almost always yes. For inheritance and estate tax, it is almost always no.
Bilateral income tax treaties are near-universal among developed countries — most major economies have 50–80 or more. Bilateral estate and inheritance tax treaties are a small, specialist subset covering a fraction of the corridors that matter. For the overwhelming majority of cross-border families, any double taxation they face on a cross-border estate is resolved only by incomplete unilateral domestic credit rules — if at all.
Principle 01 — The scale of the gap
| Country | ~Bilateral estate/IHT treaties | ~Bilateral income tax treaties | Treaty coverage ratio |
|---|---|---|---|
| United States | ~15 | ~65 | 23% |
| France | ~30 | ~125 | 24% |
| Germany | ~20 | ~100 | 20% |
| United Kingdom | ~10 | ~130 | 8% |
| Netherlands | ~12 | ~95 | 13% |
| Japan | ~5 | ~75 | 7% |
| Most other states | 0–5 | 40–80 | <10% |
Principle 02 — What happens without a treaty: unilateral credit only
Where no bilateral estate tax treaty exists, double taxation is addressed only by each country’s domestic unilateral credit rules. These provide partial relief but are frequently incomplete:
Principle 03 — The most exposed no-treaty corridors
- UK/Spain: No DTA. UK LTR tail + Spanish ISD both potentially claim Spanish assets. Unilateral credit only.
- UK/Portugal: No DTA. UK LTR tail + Portuguese Imposto do Selo. Unilateral credit only.
- UK/Italy: No DTA. UK IHT + Italian succession tax. Azione di riduzione retroactive risk.
- France/Australia: No DTA. AU CGT + French succession tax. Different tax types, different events, different taxpayers — near-zero credit availability.
- US/entire Latin America: No US estate treaty with any Latin American country.
- Germany/Spain: No DTA. German 10-year shadow + Spanish ISD. One of the most common unplanned European corridors.
- AU/Southeast Asia: No estate DTA with Indonesia, Philippines, Thailand, Vietnam, or Malaysia.
Principle 04 — The well-served corridors
A small number of bilateral corridors have genuinely effective estate tax treaties that substantially reduce double taxation:
- UK/Ireland (1978): Domicile tie-break, situs allocation, bilateral credits. The most effective bilateral instrument in Europe for this purpose.
- UK/Netherlands: Structured DTA with credits both ways.
- Germany/Austria: Austria has no inheritance tax (abolished 2008). DTA allocates assets cleanly. After Germany’s 10-year shadow expires, this corridor becomes genuinely low-risk.
- Germany/France (1959): Provides structured relief — predates modern fiscal domicile rules but remains useful for the bilateral frame.
- US/UK (1978), US/France (1978), US/Germany (1982): Structured US-bilateral instruments — but with citizenship carve-outs that limit benefit for US citizens.
The default assumption for any cross-border estate should be: two countries are taxing this estate. Relief is partial. The question is not whether double taxation exists — it is how much residual double taxation remains after applying whatever unilateral and bilateral relief is available.
Planning triggers — you should be reviewing this if…
- You have connections to two countries and assume a tax treaty resolves double taxation — check whether an estate/IHT treaty (not just an income tax treaty) actually exists
- You are in a UK/Spain, UK/Portugal, UK/Italy, AU/France, or Germany/Spain corridor — no estate DTA
- You are in Latin America as a US citizen — no US estate treaty exists anywhere in the region
- You have been told “there’s a tax treaty” — confirm it is an estate or inheritance tax treaty, not just an income tax treaty
Frequently Asked Questions
Is there a tax treaty between the UK and Spain for inheritance tax?
No. There is no bilateral inheritance or estate tax treaty between the UK and Spain. Any double taxation between UK IHT and Spanish ISD is resolved by unilateral domestic credit rules only — UK s.159 IHTA 1984 and Spanish domestic credit provisions — which may leave a residual gap. This is one of the most common high-exposure no-treaty corridors given the large UK expat community in Spain.
Is there a tax treaty between the UK and Portugal for inheritance tax?
No. There is no bilateral inheritance or estate tax treaty between the UK and Portugal. Any double taxation between UK IHT (if within the LTR tail) and Portuguese Imposto do Selo is resolved by unilateral credit only. This is particularly significant for UK nationals who moved to Portugal under the NHR regime, many of whom are now within the UK LTR departure tail with no treaty protection.
Does a bilateral income tax treaty cover inheritance tax?
No. Income tax treaties and estate/inheritance tax treaties are entirely separate instruments. Most countries have extensive income tax treaty networks (50–130 treaties) but very sparse estate/inheritance tax treaty coverage (typically 5–30 treaties). An income tax treaty between Country A and Country B does not provide any relief from estate or inheritance taxes — even if it covers the same two countries.
Which UK bilateral estate tax treaties are currently in force?
The UK has bilateral estate and gift tax treaties with approximately 10 countries, including: Ireland (1978), Netherlands, France (1963, limited scope), USA (1978), South Africa, India (limited and income-focused), Sweden, Switzerland (limited), Pakistan, and Italy (limited historical treaty). These treaties vary significantly in their scope and effectiveness. The UK/Ireland 1978 treaty is generally considered the most effective.
Why doesn’t the US have an inheritance tax treaty with Mexico?
The US has no bilateral estate or inheritance tax treaty with any Latin American country — not Mexico, Colombia, Brazil, Argentina, Chile, or Peru. This is a longstanding gap in the US bilateral treaty network. US citizens living in any of these countries face worldwide US estate tax with no structured bilateral relief. All mitigation relies on US domestic credit rules, which provide limited protection.
FAQs for educational purposes only. Not legal, tax or financial advice.
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