What to check before you buy an ETF: eight things that differ between two funds tracking the same index

Two funds, one index, different answers

Most of what an ETF does is decided before you ever look at its performance: how it is built, where it lives, what it does with the dividends, and what all of that costs. Two funds can track the very same index and still leave a Belgian investor with different paperwork, different taxes and different risk. This is a checklist of the eight properties worth reading off a fund's own documents before you buy — what each one means, and where the honest trade-off sits.

To keep it concrete, one pair runs through the whole piece: Vanguard FTSE All-World UCITS ETF, which exists in two share classes — VWCE (accumulating, ISIN IE00BK5BQT80) and VWRL (distributing, ISIN IE00B3RBWM25). Same provider, same index, same 0.22% ongoing charge, same Irish domicile, same physical replication. The only thing that differs is what happens to the dividends — and that one difference is enough to change your Belgian tax.

1. Accumulating or distributing

An accumulating share class reinvests the dividends inside the fund; a distributing one pays them into your account. Over a long horizon the before-tax return is close to identical — the money is the same, it simply either compounds silently or lands as cash you reinvest yourself.

For a Belgian resident the difference is not in the return but in two taxes:

• The stock exchange tax (TOB). The 1.32% rate applies only when both are true: the fund is registered in Belgium and the share class accumulates. A distributing share class of the same fund is usually 0.12% — a factor of eleven on every buy and sell. Neither condition can be read off the ISIN, and the two share classes each carry their own. How the rate is decided is set out in how the TOB rate on an ETF is determined, and what we have established fund by fund is in the ETF tax snapshot.
• Dividend withholding. A distributing fund produces a dividend, and where the 30% Belgian withholding is not deducted at source it goes on your annual return every year. An accumulating fund produces no dividend line, so there is nothing to declare until you sell.

So the honest picture is a swap of one cost for another: accumulating spares you the yearly dividend admin but can attract the 1.32% TOB; distributing keeps the TOB low but hands you a taxable dividend each year. Which one is cheaper depends on the fund's registration and on how much you value not filing. The mechanics of telling the two apart in your own portfolio are in accumulating or distributing — which do I hold, and the worked tax comparison in accumulating vs distributing: an S&P 500 ETF and the Belgian tax.

2. Physical or synthetic (swap-based) replication

A physical ETF owns the shares in the index, all of them or a representative sample. A synthetic one holds a basket of collateral and signs a total-return swap with a bank that pays it the index's return. Two consequences follow, and they point in opposite directions.

• Counterparty risk. A swap is a promise from a bank. Under UCITS the exposure to any one counterparty is capped at 10% of the fund and collateralised, so the risk is bounded — but it exists, where a physical fund's risk is simply that of the shares it holds.
• Withholding efficiency. For some US indices, a swap can deliver the gross index return without the US dividend withholding a physical fund pays. On the S&P 500 that drag is real: a physical Irish fund loses 15% of roughly a 1.2% dividend yield, near 0.18% a year, while a well-structured swap fund can avoid most of it. The same withholding logic sits behind foreign dividend withholding and the W-8BEN.

You can see the trade-off in a real S&P 500 pair, both Irish and both accumulating: Invesco S&P 500 UCITS ETF (synthetic, ISIN IE00B3YCGJ38, 0.05% ongoing charge) against iShares Core S&P 500 UCITS ETF (physical, ISIN IE00B5BMR087, 0.07%). The synthetic fund's lower cost and withholding advantage are bought with counterparty exposure the physical fund does not carry. Neither is the "right" structure; they price the same index differently and take different risks to do it.

3. Domicile and Belgian registration

Where the fund is legally established — almost always Ireland or Luxembourg for the funds Belgians buy — is not cosmetic.

• Treaty rate on US dividends. An Irish-domiciled fund pays 15% US withholding under the US–Ireland treaty, against 30% for a domicile with no treaty. For a fund heavy in US shares that difference is a permanent, invisible drag.
• UCITS protection. A European UCITS fund carries the diversification and liquidity rules of that regime. A US-listed ETF (a different thing with a similar name) is generally not available to retail buyers in the EU and follows another tax logic entirely.
• Belgian registration. Whether the fund is on the Belgian register is one of the two conditions for the 1.32% TOB from point 1. It is a property of the fund, not of your broker, and it is the one people most often assume rather than check.

VWCE and VWRL are both Irish UCITS funds; the registration status is what you verify against the ETF tax snapshot before assuming a rate.

4. The ongoing charge (TER)

The Total Expense Ratio is the yearly percentage the fund takes out of its own value. You never see an invoice; it is already inside the price. VWCE and VWRL both charge 0.22%; the S&P 500 pair above charge 0.05% and 0.07%.

Two honest cautions. First, the TER is not the whole cost — the broker's transaction fee and the stock exchange tax sit on top, and only the broker fee changes when you switch broker. Second, a lower TER does not guarantee a cheaper fund to hold, which is what the next point is about.

5. Tracking difference

The TER is what the fund charges; the tracking difference is what it actually delivered against its index after everything — fees, withholding, securities lending, sampling. It is frequently larger than the gap in TER between two funds, and it can even be positive when securities-lending income more than covers costs. A fund with a 0.20% TER and a 0.10% tracking difference has been cheaper to hold than one with a 0.07% TER and a 0.25% difference. Published on the provider's factsheet as a multi-year figure, it is the number that says what the fund cost in practice rather than on paper.

6. Fund size and liquidity

A fund's assets under management and its trading spread decide two prosaic things: whether it is likely to stay open, and what it costs to get in and out.

• A very small fund can be closed and liquidated by its provider — not a loss of your money, but a forced sale on someone else's timing, which can land a taxable event when you did not choose one.
• The bid–ask spread is a cost paid on every trade, on top of the broker fee and the TOB. A large, heavily traded fund tends to have a spread of a fraction of a percent; a thin one can cost more to trade than a year of its TER.

VWRL, the older and larger of the pair, has traded since 2012; VWCE launched in 2019. Both are large by now — but on a niche fund this is the check that catches a closure or a wide spread before it catches you.

7. Share price

The price of one share — a few euros against a few hundred — changes almost nothing about the investment and a little about the mechanics. The stock exchange tax is a percentage, so it is identical whether you buy one €300 share or thirty €10 ones. Most brokers' fees are percentage-based too, and equally price-neutral.

It matters only in two places: a broker charging a fixed fee per order makes many small shares relatively expensive, and a broker without fractional shares forces you to buy whole units, so a high share price can leave uninvested cash. A high price per share is not "expensive" in any sense that affects return — VWCE trades higher than VWRL only because it keeps the dividends the other pays out.

8. The index and its method

Last, the thing the fund actually tracks — which two funds with similar names can define very differently. FTSE All-World (VWCE/VWRL) holds around 3,700 companies across developed and emerging markets. MSCI World — tracked by, for instance, the iShares Core MSCI World UCITS ETF (IWDA, ISIN IE00B4L5Y983, 0.20%) — holds roughly 1,400 companies in developed markets only, with no emerging exposure at all. Same "world" in the name, materially different holdings. Screened or ESG variants narrow the list further. Reading which index a fund tracks, and what that index includes, is what stops two funds that look interchangeable from quietly being two different bets.

Where to read each of these

Every property above is on a document you can pull before buying:

• The KID (Key Information Document) — mandatory, one page: ongoing charge and risk indicator.
• The factsheet — replication method, domicile, fund size, index, and the multi-year tracking difference.
• The provider's page or a fund screener — distribution policy and TER at a glance.
• The ETF tax snapshot — the Belgian stock exchange tax we have established per fund, with a source on each row and a plain "we do not know" where we could not.

To see the stock exchange tax on a specific order before you place it, the stock exchange tax simulator computes it from that same data; the calculator does it for a whole portfolio from a broker export.

The pair, side by side

Property	VWCE	VWRL
Index	FTSE All-World	FTSE All-World
Dividends	Accumulating (reinvested)	Distributing (paid out)
Ongoing charge (TER)	0.22%	0.22%
Domicile	Ireland (UCITS)	Ireland (UCITS)
Replication	Physical	Physical
ISIN	IE00BK5BQT80	IE00B3RBWM25
Trading since	2019	2012
Belgian tax difference	No yearly dividend; check TOB rate on the accumulating class	Yearly dividend to declare; TOB usually 0.12%

Everything but two rows is identical — which is exactly the point. The choice between them is not about which fund is good; it is about which Belgian tax and which yearly admin you would rather carry. The figures are illustrations of the mechanism; ISINs, charges and registration status change, so verify each against the fund's own documents and the snapshot before you rely on it.

Always verify your figures

Belfolio computes and presents these amounts for information only. This is not tax advice nor investment advice, and nothing here is a suggestion to buy any particular fund. Rates, ongoing charges and funds' registration status change; verify your amounts with the FPS Finance or your accountant before filing.