VOO vs CSPX for non-US investors

The two funds, side by side

Fund data as published by Vanguard, iShares and fund data providers in September 2026. Expense ratios and fund details change — the factsheet is the authority, not this page.

Unlike the global-fund comparisons, there is no index difference to argue about here: both hold the S&P 500. CSPX is the largest Irish-domiciled UCITS ETF, which is one reason it is the ticker Europeans reach for by default. Every real difference between the two is the wrapper.

Why this comparison behaves differently from the global ones

In a world fund, the Irish wrapper's advantage comes from geography: only the US slice of the dividend suffers US withholding inside the fund, while the US wrapper withholds your treaty rate on everything. An S&P 500 fund has no such split — its dividends are essentially 100% US-sourced. So the comparison collapses to 15% of everything (inside CSPX) against your treaty rate on everything (out of VOO's distribution). At exactly 15%, the two wrappers pay the same withholding; the Irish fund just pays it a layer earlier. The decision then moves to fees, foreign tax credits, estate exposure and availability. Where the split does exist — a global fund holding US and non-US stocks — the arithmetic comes out differently; VT vs VWRA works that case through on the two funds people compare most.

Where the dividend is taxed, and by whom

• VOO is a US fund. It pays no US withholding on the dividends it receives — but its distribution to you is US-source income. Your residence's rate from the IRS treaty table is applied to the entire distribution: 30% where there is no treaty or no documentation on file, 15% for many treaty countries, 10% for a few residences, 0% for a couple.
• CSPX is an Irish fund. It suffers 15% US withholding on the dividends it receives, under the US–Ireland treaty. Ireland then withholds nothing from a non-resident holder, and because the share class accumulates, nothing is paid out to withhold from in the first place.

So the question is not which wrapper avoids US withholding — neither does — but whether your personal treaty rate is above, at, or below the 15% that CSPX locks in.

A worked example, with its assumptions in the open

$100,000 invested; gross dividend yield of the index assumed 1.3%, so $1,300 a year, all of it US-sourced. The only variable left is your treaty rate.

Now add the fee gap: 0.03% against 0.07% is four basis points — $40 a year on $100,000 in VOO's favour. For a no-treaty residence that barely dents CSPX's $195 withholding advantage. At 15%, where withholding is a wash, the fee gap is the whole visible difference, and VOO is ahead on total annual drag. At 10% or 0%, VOO wins on both counts. Find your residence's rate — it is a published number, not an estimate.

The foreign tax credit can break the 15% tie

The table above treats the two $195 figures as equivalent, and mechanically they are — the same dollars reach Washington. But they are not equivalent to every tax office. Withholding on a distribution paid to you (VOO's case) is often creditable against the tax your residence charges on the same dividend. The 15% suffered inside CSPX generally is not — the fund paid it, not you, and most credit systems only recognise tax you suffered directly. A residence that taxes dividend income and grants foreign tax credits can therefore recover part of VOO's withholding while recovering none of CSPX's, tilting the 15% case towards VOO by more than the fee gap alone. A residence that taxes nothing gets no credit either way, and the table stands as written. Whether your residence grants the credit, and with what caps, is a home-tax question this page does not model.

Estate tax: the asymmetry that is not about percentages

VOO shares are US-situs assets. For a non-US, non-resident estate, US-situs assets above USD 60,000 can attract US estate tax at rates reaching 40% on the excess, unless an estate tax treaty raises that threshold — and the United States has estate treaties with only a limited number of countries. CSPX, as an Irish-domiciled UCITS, is not a US-situs asset for this purpose.

A long-term index investor crosses $60,000 in an ordinary month, with no notification from the broker and no change of state anywhere on a dashboard. Whether it ever bites depends on how the assets are held and on the circumstances of an estate, which is not something any tracker can compute — but for many holders this asymmetry outweighs a few tens of dollars of annual drag in either direction.

Accumulating is not automatically simpler

CSPX reinvests internally: no cash lands, nothing to re-buy, no drag from idle dividends, and — usefully for a contribution tracker — nothing that could be mistaken for a deposit. But several residences tax accumulating funds anyway, on a deemed or imputed basis rather than on cash received, and a few tax them less favourably than distributing ones. VOO's quarterly distribution is visible, taxable in the ordinary way, and has to be reinvested by hand.

Which is better depends on the residence you actually have, not on which is tidier.

Whether you can buy either one

Availability decides this question more often than arithmetic does. Retail investors in the EEA and the UK generally cannot buy VOO, because US-domiciled ETFs do not publish the KID that PRIIPs requires; European brokers block the order rather than the regulator blocking the fund. That restriction is a large part of why CSPX became the default S&P 500 building block for European investors. Investors in most other jurisdictions can typically buy either through an international broker, subject to the broker's own rules.

If only one of them is purchasable where you are, the comparison is already settled, and the useful question becomes what the wrapper costs you per year — which is what the numbers above are for.

CSPX or VUAA?

If you have landed on the Irish wrapper, the follow-up question is usually which one. CSPX and VUAA are near-interchangeable: same index, same 0.07% TER, both Irish-domiciled and accumulating, so everything on this page about withholding, estate situs and availability applies identically to both. The practical differences are fund size, issuer and trading spread, not tax.

A different follow-up is whether the S&P 500 is the exposure you actually wanted. Anyone coming from VTI is used to owning the whole US market rather than its largest 500 companies, and there is no UCITS fund that does that — the VTI page sets out how much the S&P 500 route leaves out and what it costs to add it back.

What to do once you have chosen

Both effects on this page are invisible on a brokerage statement. Fund-level withholding never appears anywhere — it is deducted before the fund is paid — and investor-level withholding shows up as a line you notice once and forget. BorderFolio estimates both steps per instrument, using the domicile of each fund you actually hold against the tax residence you configure, and keeps the estimate attached to your real dividend history rather than to a hypothetical portfolio. If you hold both wrappers, or you moved and now hold the wrong one for your new residence, that is precisely the case it is built for.

Limitations

• The example is an illustration, not your portfolio. The index yield moves every year, and 1.3% is an assumption, not a forecast.
• Treaty rates depend on paperwork. Without valid documentation on file the statutory 30% applies whatever the treaty table says.
• The second step is not modelled here. Tax where you live, foreign tax credits and their caps, and the treatment of accumulating funds are all residence-specific.
• Not advice. This is an informational comparison of two fund structures, not a recommendation to buy or sell either. See the investment & tax disclaimer.

Common questions

Is CSPX better than VOO for non-US investors?

It depends on your treaty rate. Because an S&P 500 fund's dividends are essentially all US-sourced, a residence with a 15% treaty rate pays the same withholding through either wrapper — CSPX just pays it inside the fund. Below 15% (a 10% rate, or one of the rare 0% treaties) VOO withholds less, and its 0.03% expense ratio also undercuts CSPX's 0.07%. With no treaty, VOO loses 30% of the whole distribution against roughly 15% suffered inside CSPX. Estate exposure and availability can settle the question before any of that arithmetic matters.

Do VOO and CSPX pay the same withholding at a 15% treaty rate?

Essentially yes. VOO's distribution is US-source income withheld at your treaty rate — 15% of everything. CSPX suffers 15% US withholding inside the fund under the US–Ireland treaty, and Ireland withholds nothing from non-residents. Since an S&P 500 fund's dividends are essentially 100% US-sourced, 15% of everything is the same amount either way; the Irish fund simply pays it a layer earlier. One second-order difference remains: withholding on a distribution paid to you is often creditable against home tax, while tax suffered inside a fund generally is not.

Is CSPX subject to US estate tax?

CSPX is an Irish-domiciled UCITS and is not a US-situs asset, so it sits outside the US estate tax net for a non-US, non-resident holder. VOO is US-situs: above USD 60,000 of US-situs assets, such an estate can face US estate tax at rates reaching 40% on the excess, unless an estate tax treaty raises the threshold.

What is the difference between CSPX and VUAA?

Very little that matters for tax. Both are Irish-domiciled accumulating UCITS ETFs tracking the S&P 500 at a 0.07% TER, so withholding, estate treatment and availability are identical. The practical differences are fund size — CSPX is the largest Irish-domiciled UCITS ETF — issuer (iShares vs Vanguard) and trading spread.