US–Ireland cross-border inheritance & estate tax

When an estate or lifetime gift touches both the United States and Ireland, two tax systems can reach the same assets. Here is how each one works in 2026, how double taxation is relieved, and the traps that most often catch cross-border families.

Reflects 2026 rules · an estimate, not advice.

Who is taxed on worldwide assets?

Both countries tax some people on their worldwide estate and others only on assets located there. Get that classification wrong and every number is wrong.

The US side — 2026 figures

• Citizens & domiciliaries are taxed on their worldwide estate and gifts; non-resident aliens only on US-situs assets (US real estate, US company shares, tangible US property). US bank deposits and life insurance are exempt (IRC §2105).
• $15,000,000 unified estate & gift exemption per person; 40% top rate on the excess.
• Portability (DSUE) lets a surviving spouse carry a predeceased spouse's unused exemption — up to a combined $30M — for estate and gift tax (not GST).
• $19,000 annual gift exclusion per recipient; NRAs get only a $60,000 exemption-equivalent (~$13k credit) absent treaty relief.
• 16 US states plus DC levy their own death taxes on top of the federal tax.

The Ireland side — 2026 figures

• Capital Acquisitions Tax (CAT) at 33% on the beneficiary, above lifetime group thresholds: Group A (child) €400,000, Group B €40,000, Group C €20,000.
• Thresholds are lifetime and aggregate benefits within the same group since 1991.
• €3,000 annual small-gift exemption per donor per recipient.
• Agricultural & Business Relief can reduce qualifying values by up to 90% (a €10M cap applies from 2025, excess relieved at 80%).

Relieving double taxation

The US–Ireland estate tax treaty (1951) — estates only — allocates taxing rights and relieves double taxation between US estate tax and Irish CAT.

The traps that catch US–Ireland families

• Situs of shares. Shares in a US company are US-situs for a non-resident alien even if held through a foreign broker — a common six-figure surprise.
• The non-citizen spouse. The unlimited US marital deduction does not apply to a non-US-citizen spouse without a QDOT.
• Double filing. A US person's foreign estate can still owe US Form 706; a large gift/bequest from a foreign person to a US recipient can trigger US Form 3520.

See your own numbers

HeirCalc models the US and Ireland sides together — applying the exemptions, residence and situs rules and any treaty relief — and shows the exposure in each country with the statutory reason behind every figure. It runs entirely in your browser; nothing is saved or sent anywhere.

This guide is general information for 2026, not legal, tax, or financial advice. Cross-border estate and gift tax turns on precise facts — residence, domicile, situs, treaty positions, trusts and forced-heirship rules — that can change the outcome. Confirm your situation with a qualified cross-border professional. HeirCalc is an estimator by Krometis Analytics.