Lifetime CAT Aggregation: How Three Earlier Gifts Push a €380,000 Inheritance Into Tax
Ireland's CAT aggregation rules treat your lifetime as one running total: every taxable gift and inheritance you receive within the same group threshold since 5 December 1991 is added together, and only what's left of the threshold shelters the next benefit. So an inheritance that looks tax-free on its own can be fully taxable once earlier gifts have already used up part of your allowance. This guide walks the maths with a real example.
What the aggregation rule actually says
Capital Acquisitions Tax (CAT) is not charged benefit-by-benefit in isolation. Revenue's rule is that, when you receive a new gift or inheritance, you must add together the taxable value of all the gifts and inheritances you've ever received in the same group threshold on or after 5 December 1991 — no matter who they came from. CAT at 33% then applies to the part of that cumulative total that sits above your group threshold.
In Revenue's own words, "the total taxable value of benefits taken is calculated by aggregating the taxable value of all previous gifts or inheritances taken within the same group threshold on, or after, 5 December 1991." (See the official CAT thresholds, rates and aggregation rules page.)
Three numbers do all the heavy lifting here, and all are verified against Revenue for benefits taken on or after 2 October 2024:
| Element | Figure | Source |
|---|---|---|
| Group A threshold (parent → child) | €400,000 | Revenue – CAT group thresholds |
| Group B threshold (sibling, niece/nephew, grandchild) | €40,000 | Revenue – CAT group thresholds |
| Group C threshold (everyone else) | €20,000 | Revenue – CAT group thresholds |
| CAT rate above threshold | 33% | Revenue – CAT rates (since 6 Dec 2012) |
| Aggregation start date | 5 December 1991 | Revenue – aggregation rules |
Anything received before 5 December 1991 is invisible to the aggregation calculation. A gift your parents made you in 1989 doesn't reduce today's threshold. Only benefits taken on or after that date enter the running total.
Worked example: Aoife's €380,000 inheritance
Aoife is an only child. Over the years her parents helped her along — and now her father has died, leaving her €380,000. On its own that's below the €400,000 Group A threshold, so Aoife assumes there's no CAT. The aggregation rule says otherwise, because she has three earlier Group A benefits on the clock:
- 2016 — €20,000 towards a house deposit (from her mother).
- 2019 — €15,000 towards her wedding (from her father).
- 2022 — €15,000 to clear a car loan (from her mother).
All three are gifts from a parent, so they sit in Group A — the same group as the inheritance. Each was bigger than the annual €3,000 small-gift exemption, so the exempt slice is stripped out and only the excess counts (we cover this in detail below).
Step 1 — Strip out the small-gift exemption on each prior gift.
| Year | Gift | Less €3,000 exemption | Counts toward Group A |
|---|---|---|---|
| 2016 | €20,000 | −€3,000 | €17,000 |
| 2019 | €15,000 | −€3,000 | €12,000 |
| 2022 | €15,000 | −€3,000 | €12,000 |
| Prior Group A used | €41,000 |
Step 2 — Work out the threshold still available.
€400,000 threshold − €41,000 already used = €359,000 of threshold remaining to shelter the inheritance.
Step 3 — Aggregate the new inheritance with the running total.
Cumulative Group A benefits = €41,000 (prior gifts) + €380,000 (inheritance) = €421,000.
Step 4 — Tax the excess over €400,000.
€421,000 − €400,000 threshold = €21,000 taxable.
€21,000 × 33% = €6,930 CAT due.
So a €380,000 inheritance that looked completely tax-free actually carries a €6,930 bill — entirely because three modest gifts had already nibbled €41,000 off the threshold. Aoife also crosses the filing line (see below) and must submit an IT38 return.
Notice the rounder version of this that you'll often see quoted: "€50,000 of prior Group A gifts means only €350,000 of threshold remains." That's the same mechanic — the prior benefits reduce the threshold euro-for-euro, then the new benefit gets taxed on whatever pokes above it.
The €350,000-remaining version, side by side
| Scenario | Prior Group A used | Threshold remaining | If a €380,000 inheritance follows |
|---|---|---|---|
| No prior gifts | €0 | €400,000 | €0 CAT (fully sheltered) |
| Aoife (this example) | €41,000 | €359,000 | €6,930 CAT |
| Bigger prior gifts | €50,000 | €350,000 | (€430,000 − €400,000) × 33% = €9,900 CAT |
How the small-gift exemption is excluded from the running total
This is the part most people get wrong. The small-gift exemption lets you receive up to €3,000 per calendar year from any one person completely free of CAT. Crucially, Revenue states that gifts within this €3,000 limit "are not taken into account in computing tax and are not included for aggregation purposes." (See Revenue's Small Gift Exemption page.)
So the exemption does two jobs at once: it removes the first €3,000 from tax, and it keeps that €3,000 out of your lifetime cumulative total forever. Three points to keep straight:
- It's per donor, per calendar year. A child receiving €3,000 from their mother and €3,000 from their father in the same year has €6,000 fully exempt and aggregation-free.
- Only the excess over €3,000 aggregates. Where a gift exceeds €3,000, only the amount above €3,000 is "taken into account for calculating CAT" — which is exactly why each of Aoife's gifts contributed €3,000 less than its face value to her running total.
- It applies to gifts, not inheritances. The small-gift exemption is available for gifts only. An inheritance does not get a €3,000 reduction.
Without the small-gift exemption, Aoife's three gifts would have added the full €50,000 to her running total, leaving €350,000 of threshold and producing €9,900 of CAT on the inheritance. The €3,000-per-gift exclusion shaved €9,000 off the cumulative figure, cutting her bill from €9,900 to €6,930 — a €2,970 difference from a rule she didn't even have to claim on a return.
Why each group (A, B, C) keeps its own separate running total
The cumulative total is calculated group by group, not across your whole life. You have three independent buckets, each with its own threshold and its own running total since 5 December 1991:
| Group | Relationship to the person giving | Threshold |
|---|---|---|
| Group A | Child (incl. certain foster children) receiving from a parent | €400,000 |
| Group B | Brother, sister, niece, nephew, grandchild, lineal ancestor/descendant | €40,000 |
| Group C | Any other relationship (cousins, friends, in-laws, etc.) | €20,000 |
Because the buckets are separate, a gift from a parent (Group A) never touches the threshold you'd use for a gift from an aunt (Group B). If Aoife later inherited €30,000 from an uncle, that would run against her Group B €40,000 threshold — a clean, untouched allowance — even though her Group A bucket is already over the line. You only aggregate "like with like" within the same group.
People assume "I've already paid CAT once, so the next gift from a different relative is fine." It depends entirely on which group that relative falls into. A second Group A benefit keeps stacking on the Group A total; a Group B benefit starts fresh against the €40,000 Group B allowance.
Recalculating CAT when a new benefit tips you over the threshold
When a fresh benefit pushes your cumulative group total above the threshold, you don't recompute tax on the earlier benefits — those have already been assessed. Instead you tax the new excess. The mechanic is:
- Add the new benefit's taxable value to your existing cumulative total for that group.
- Apply 33% to the slice of that cumulative total that now sits above the threshold.
- Subtract any CAT already paid on earlier benefits in the same cumulation, so the same euros aren't taxed twice.
Suppose Cian (Group A, only child) had already received €390,000 of taxable Group A benefits over his lifetime — just under the €400,000 threshold, so €0 CAT so far. His mother then gifts him €30,000 (less the €3,000 small-gift exemption = €27,000 taxable).
- New cumulative total: €390,000 + €27,000 = €417,000.
- Excess over €400,000 threshold: €17,000.
- CAT on this benefit: €17,000 × 33% = €5,610.
Only €17,000 is taxed — the €390,000 that fitted under the threshold stays sheltered, and because no CAT was paid before, there's nothing to credit back. Every future Group A benefit Cian receives will now be taxed in full at 33% from the first euro, because his threshold is completely exhausted.
When do you have to file an IT38?
You must file a CAT IT38 return once the cumulative taxable value of your benefits in a group exceeds 80% of that group's threshold — even if no tax is actually due yet. For Group A that trigger is 80% × €400,000 = €320,000. Aoife (€421,000 cumulative) is well past it; so was Cian. Filing is also required if you're claiming agricultural or business relief, regardless of the 80% test. See Revenue's aggregation rules page.
- Your lifetime is one running total per group — every gift and inheritance in the same group since 5 December 1991 aggregates, regardless of who gave it.
- Prior benefits shrink your threshold euro-for-euro. €41,000 of earlier Group A gifts leaves €359,000 to shelter the next benefit; €50,000 leaves €350,000.
- The €3,000 small-gift exemption is excluded from aggregation — per donor, per calendar year, gifts only. Only the excess over €3,000 enters the running total.
- Groups A, B and C are separate buckets. A Group A benefit never uses up a Group B threshold.
- CAT is 33% on the excess over the threshold, and you must file an IT38 once your cumulative group total passes 80% of the threshold (€320,000 for Group A).
Frequently asked questions
Do gifts and inheritances aggregate together, or separately?
They aggregate together. CAT makes no distinction between a gift and an inheritance for cumulation purposes — both count toward the same group threshold. The only difference is that the €3,000 small-gift exemption applies to gifts, not inheritances.
Does a gift from my mother and a gift from my father go into the same running total?
Yes. Both parents are Group A, so gifts from either (or an inheritance from either) all pool into your single Group A cumulative total. The €3,000 small-gift exemption, however, is counted per person — so €3,000 from each parent in the same year is exempt and excluded from aggregation.
Do gifts from before 5 December 1991 count?
No. Only benefits taken on or after 5 December 1991 enter the aggregation calculation. Anything earlier is ignored entirely, so it does not reduce your available threshold today.
If I've used up my Group A threshold, can I still receive from a sibling tax-free?
Potentially, yes. A benefit from a sibling falls into Group B, which has its own separate €40,000 threshold and its own running total. Exhausting Group A has no effect on the Group B allowance.
Do I have to recalculate tax on my earlier gifts when a new one tips me over?
No. You only tax the new excess above the threshold. CAT already correctly paid on earlier benefits in the same cumulation is credited so the same value isn't taxed twice — you don't reopen settled assessments.
When must I file an IT38 return?
When your cumulative taxable benefits in a group exceed 80% of that group's threshold — €320,000 for Group A, €32,000 for Group B, €16,000 for Group C — or whenever you're claiming agricultural or business relief, regardless of that 80% test.
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