UK–Ireland cross-border inheritance & estate tax

When an estate or lifetime gift touches both the United Kingdom 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 UK side — 2026 figures

• From 6 April 2025 IHT is residence-based: a long-term resident (UK-resident 10 of the last 20 years) is within IHT on their worldwide estate — otherwise only UK-situs assets.
• £325,000 nil-rate band plus up to £175,000 residence nil-rate band (tapered away above a £2M estate); 40% above the threshold (36% if 10%+ to charity).
• Unlimited spouse/civil-partner exemption to a UK-domiciled or long-term-resident spouse; otherwise capped without a s.267ZA election.
• Business & Agricultural Relief: from 6 April 2026, 100% relief capped at £2.5M of qualifying assets (transferable to £5M between spouses), 50% above; AIM shares 50%.
• Lifetime gifts can be tax-free after 7 years (the PET rule); unused pensions enter IHT from 6 April 2027.

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 UK–Ireland convention (1978) prevents the same assets being fully taxed by both UK IHT and Irish CAT, with credit relief.

The traps that catch UK–Ireland families

• The 2025 residence test. A long-term resident can pull their entire worldwide estate into UK IHT once past the 10-of-20-year line — often without realising the old non-dom shelter is gone.
• The spousal cap. Leaving assets to a spouse who is not UK-domiciled or long-term-resident can lose the unlimited exemption without a s.267ZA election.

See your own numbers

HeirCalc models the UK 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.