Did some calculations on a hypothetical SIA vs a CGT product (with and without annual harvesting, no dividends) vs an ETF exposed to DD. Ran it over 8 and 16 years to see the impact of DD in particular. Then had a look at pension.
Assumptions:
- €12,000 in at the start of each year, 10% annual gain straight line after fees (i.e., didn't bother to explore fees! If fees for the SIA are materially higher than other options, then the math will change).
- Budget 2027 rates in perpetuity: CGT 31% with the €1,270 exemption, DD/exit tax 35%, SIA 1% on the value above €50k
- Rates and the €50k threshold stay fixed
- SIA tax taken at year end from the account (the mechanics await the Finance Bill)
- Annual harvesting means selling enough to realise €1,270 of gain each year and buying straight back. The four-week rule only restricts losses, and this scenario is a highly realistic straight line gain

- No consideration of dividends or capital loss treatment, nothing to say on inflation. This is a straight arrow exercise.
- I'm assuming you live to enjoy the proceeds and aren't bothered about avoiding tax upon death. And we don't really know how the SIA will be handled in the event of death, anyway.
| SIA | CGT product | CGT product with annual harvesting | ETF (DD) |
|---|
| 8 years (€96,000 in, €150,954 gross, €54,954 gain) | | | | |
| Tax paid | €2,662 | €16,642 | €13,908 | €19,234 |
| Net proceeds | €147,957 | €134,312 | €137,046 | €131,720 |
| Shortfall vs gross, as % of gain | 5.5% | 30.3% | 25.3% | 35.0% |
| Behind SIA by | n/a | €13,645 | €10,911 | €16,237 |
| 16 years (€192,000 in, €474,536 gross, €282,536 gain) | | | | |
| Tax paid | €22,614 | €87,193 | €81,309 | €91,189 |
| Net proceeds | €441,749 | €387,344 | €393,228 | €361,352 |
| Shortfall vs gross, as % of gain | 11.6% | 30.9% | 28.8% | 40.1% |
| Behind SIA by | n/a | €54,406 | €48,522 | €80,398 |
"Shortfall vs gross" is the gap between what you end up with and the untaxed pot. It is bigger than tax paid where tax is taken along the way, because that money stops compounding.
SIA is pretty advantageous. Its tax ramps up considerably after year 8 because the 1% applies to everything above a fixed €50k, and that slice quadruples between years 8 and 16 while the pot only triples.
So the next question would be, when does the SIA stop making sense in this scenario?
Against an ETF, basically never so long as DD exists.
Against a CGT product, not for a very long time. At 10% the CGT product doesn't overtake until around year 49. And 10% is not doing the heavy lifting: over 24 years the SIA wins at any return above roughly 3%. And in reality a lot of CGT-able products will come with dividends, and the swing will heavily favour the SIA then.
What about each extra euro above the threshold?
| Holding period | Annual return needed for SIA to win |
|---|
| 8 years | 3.7% |
| 16 years | 4.2% |
| 24 years | 5.0% |
| 32 years | 7.1% |
| 37+ years | CGT wins |
So above the threshold, low-return assets and money you won't touch for 35+ years are better off outside the SIA in a CGT product.
Again this assumes no dividends, which would markedly change the picture if they were part of the 10% annual returns assumed in the scenario.
Risk
The SIA charges 1% even in down years, while CGT only taxes gains. Take the same €12k a year over 24 years (€288k in). In a flat market you'd get your €288k back from the CGT product but only about €265k from the SIA, so about €23k worse off. At 5% a year you'd be about €25k better off in the SIA (€502k vs €477k), and at 10% about €127k better off (€1.02m vs €896k). So above the threshold it comes down to whether you expect better than about 3% a year.
Dividends
Of course, if you held a basket of shares that paid dividends, those would be exposed to your top marginal rate (call it 52% for anyone with money to invest) outside the SIA and to nothing inside it, which would swing things further to the SIA. Pick a % of gains from dividends and slice off 52% and run into the calcs to see the impact, but favourable to the SIA probably.
Pension
Same exercise: €12k a year of take-home pay for 16 years at 10%. A 40% taxpayer gets €20k a year into the pension for the same net cost, so the pension pot is €791k vs €442k in the SIA. The pension gets both upfront relief and tax-free growth; the SIA gets neither relief nor fully tax-free growth above €50k.
| Scenario | Net proceeds | vs SIA |
|---|
| SIA | €441,749 | n/a |
| Pension: 25% tax-free lump sum, rest at 23% (20% + 3% USC) | €654,465 | +€212,715 |
| Pension: 25% tax-free lump sum, rest at 48% (40% + 8% USC) | €506,172 | +€64,423 |
| Pension: €200k tax-free band already used, lump sum taxed at 20%, rest at 48% | €466,627 | +€24,878 |
| Pension: both lump sum bands (€500k) already used, everything at 48% | €411,265 | -€30,484 |
| Pension: all of the extra pot above the Standard Fund Threshold (40% excess tax, then 48%) | about €247,000 | about -€195,000 |
So if you get 40% relief, have lump sum allowances left and are below the SFT, the pension wins comfortably. A 20% taxpayer comes out ahead too: €15k a year gross gives about €491k net, roughly €49k ahead of the SIA. Although, not sure many 20% taxpayers have this kind of money to throw around annually.
The SIA only wins on the numbers where the favourable treatment is used up: your other pensions already take you past €500k of lump sums (a fund of about €2m) and your withdrawals are at the higher rate, or the extra money would land above the SFT, or you've maxed your age-related relief.
The obvious non-financial point: the pension is locked until retirement and the SIA isn't. But you can try and calculate the cost of that flexibility.
(The tax rates are illustrative combined rates on withdrawals over retirement, with no PRSI and no further growth during drawdown. Actual rates depend on your income each year. And this post has gone on long enough, but you get the idea...)