Before you buy the 2026 theme ETF: five things that differ on a niche fund

Why a thematic fund raises different questions

Between two global index funds tracking the same index, the discussion is about eight characteristics that differ — they are in what to check before buying an ETF.

On a narrow thematic fund, questions are added that barely arise on a world fund. Not because the theme is bad — that is not what this article is about — but because the tax and structural uncertainty is systematically greater there.

This article is about what you can check, not about what you should buy.

1. The TOB rate is least predictable here

A fund's TOB rate follows from two characteristics taken together: is the fund registered with the FSMA for marketing in Belgium, and is your share class accumulating or distributing? Registration × accumulating gives 1.32%; if either is absent, 0.12%. See how the TOB rates are determined.

Registration is not domicile: an IE ISIN says nothing about it.

On the large world funds from the well-known issuers, that registration can usually be looked up. On a recent thematic fund from a smaller issuer it frequently cannot — and that is exactly where the guess is most expensive, because 1.32% against 0.12% is a factor of eleven, on every buy and every sell.

What you can do: ask your broker for the rate in advance and keep the answer. If you find two brokers taxing the same fund differently, that is not your error — it is a known consequence of a divergent reading of that same registration question.

2. Check first that it is even a fund

On single-exposure themes — one commodity, one metal, volatility — the product is often not a fund. It is then an ETN or an ETC: a debt security, not a basket of holdings. You are a creditor of an issuer rather than a unitholder in a fund.

That changes three things at once: who owns it, what happens if the issuer goes bankrupt, and which tax reaches the return. The full account is in what is an ETN.

The test is quick: if the factsheet says fund, SICAV, ICAV or UCITS, it is a fund. If it says note, certificate, debt security or senior unsecured, it is not — and the registration × class test from point 1 does not even apply to it.

3. Small funds close — and that is now a taxable moment

A thematic fund that fails to find its audience gets merged or wound up after a few years. On a world fund running tens of billions that is not a real scenario; on a niche fund of a few tens of millions it certainly is.

Before 2026 that was mainly annoying. Since 1 January 2026 it is more expensive, because the capital-gains tax attaches to the realisation — and in a closure your position is liquidated at a moment you did not choose. The result: a taxable amount in a year when you may already have sold something else, so possibly beyond your exempt tranche. See the €10,000 exemption.

Exactly how a liquidation is characterised we could not establish from a primary source. What is certain is that the timing is not yours — and in tax planning that is the part that matters.

What you can check: assets under management and the launch date. A fund of a few tens of millions that has existed for a year or two is not the same risk as a ten-billion fund that has existed for fifteen.

4. The costs that are not in the TER

Thematic funds cost more, and the published expense ratio is not the whole story:

• Ongoing charges are typically a multiple of those on a broad index fund.
• The spread — the gap between bid and ask — is wide on a thinly traded fund, and you pay it on every round trip. It appears in no cost table.
• The stock-exchange tax comes on top of that, at the rate from point 1.

For anyone investing small amounts periodically, spread and TOB together can weigh more heavily than the ongoing charges.

5. The index is younger than the chart

A thematic fund often tracks an index built specifically for that theme, sometimes shortly before the fund launched. The series you see in the presentation is then largely a backtest — not a result actually achieved.

What you can check: the index launch date next to the fund's, and how much of the displayed history was actually lived through.

The checklist

Before you buy a thematic fund:

1. Fund or debt security? Find the legal form in the factsheet or KID.
2. FSMA registration and share class. Ask for the TOB rate in advance and keep the answer.
3. Assets under management and launch date. How small, how young?
4. Ongoing charges and spread. Look at them together, not separately.
5. Index launch date. How much of the chart actually happened?
6. Currency. Many thematic funds quote in dollars and do not hedge it.
7. Overlap. Is the theme already partly inside your world fund?

Points 7 and 4 can be checked side by side in the ETF comparison.

What we deliberately do not do here

We name no rate for any specific fund in this article, and that is a choice.

The rule we can publish: registration multiplied by share class. The inputs per fund — is this particular fund registered? — are exactly what we source ISIN by ISIN and mark unconfirmed until then. Putting a per-fund rate here without that source would only push the problem onto your statement.

Nor do we name themes to buy or avoid. Which theme performs next year we do not know — what we can do is supply the questions you will read a prospectus with.

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This is general information on Belgian taxation and on reading fund documentation. It is not tax or investment advice, and not a recommendation for or against any fund or theme.