What an ETF really costs.

The price with an expiry date

A large number of funds quote a net expense ratio that is lower than their gross one, because the adviser has contractually agreed to waive part of its fee or reimburse some expenses. Both numbers are in the fee table, side by side, and the agreement behind the gap has an end date printed in a footnote.

Nothing about this is improper — it is how a new fund buys shelf space, and it is disclosed exactly as the rules require. But it means the cheapest fund in a comparison is sometimes the cheapest only until a date nobody in the comparison mentioned. A fund whose waiver ends next year and reverts to the gross figure is a different proposition from one priced there permanently, and the fee table is where you find out which you are holding.

When a fund holds a fund

A fund that gets its exposure by holding other funds pays their fees too. That is disclosed in the fee table as acquired fund fees and expenses, and it is frequently excluded from the ratio a fund quotes in its own marketing, because the two are reported on separate lines.

The result is a wrapper that looks inexpensive and is not. It is not hidden — it is one row further down the same table — but a comparison built from fact sheets will miss it every time.

What it costs the fund to trade

Funds trade, trading costs money, and that money comes out of the same assets a fee does. Commissions appear in the annual report; the prospectus publishes portfolio turnover, which is the standard proxy for how much trading is going on.

For a broad index fund that rarely rebalances, this is usually small enough to ignore — and you can only know that by looking. For anything that turns its portfolio over aggressively, it is not small, and it is the difference between the fee you compared and the cost you paid.

The cost that is yours, not the fund’s

The bid-ask spread is not charged by the fund and appears in none of its filings, because it is not the fund’s cost — it is yours, paid to the market, once when you buy and again when you sell. On a heavily traded fund it is a rounding error. On a thin one, a single round trip can cost more than a year of the expense ratio.

It also means frequency matters. A cost paid per trade punishes activity in a way an annual fee does not: a fund with a slightly higher ratio that you buy once can be cheaper than a cheaper fund you trade monthly.

The wrapper changes the tax form

"ETF" is a description of how something trades, not of what it legally is. Four wrappers dominate, and the differences between them are not cosmetic — they decide what the fund may do with your dividends and what paperwork arrives in February.

Two tax bills you did not choose

Distributed capital gains. When a fund realises gains it must pass them to shareholders, and you owe tax on them in a year you may have sold nothing at all. ETFs largely avoid this, because they can meet redemptions by handing securities to an authorised participant rather than selling them. Largely is not always: a fund that changes index, holds derivatives, or shrinks sharply can and does distribute gains. The distribution history says whether yours has.

Foreign withholding tax. A fund holding non-US securities has tax deducted at source before it ever receives the dividend. Two conditions decide whether you ever see that money again, and neither is in a fee table.

First, the fund has to be able to hand the credit to you. A fund that is majority-foreign at year end can elect to pass the foreign tax it paid through to its shareholders, and it then reports your share on the tax form you receive. A fund that falls under that statutory threshold cannot make the election at all — it absorbs the tax, and you cannot claim any of it. A global fund holding a minority of foreign stock is the case that catches people, because it looks like an international fund and is not treated as one.

Second, you have to have US tax to offset. The credit works by reducing what you owe, so inside an IRA or a 401(k) there is nothing to reduce and the withheld tax is gone — not deferred, gone. The expense ratio is identical in both accounts; the real cost of holding the fund is not. It is the clearest case on this site of a cost that no fee comparison anywhere will show you.

This describes how a published set of rules works. It is not tax advice, it accounts for nothing about your situation, and the details depend on where you file. Check anything you intend to act on with someone qualified.

What a tenth of a percent costs

Drag sounds like rounding when it is quoted as a percentage and stops sounding like rounding when it is compounded. Below, $10,000 grows at 6% a year, and the only thing that changes is how much annual drag comes off the top.

The number that nets everything

Every layer above is an input. There is one output, and funds report it: tracking difference — what the fund actually returned against what its index did over the same period. It nets the expense ratio, the trading costs, the acquired fund fees, any withholding drag and the manager’s execution into a single figure, after the fact.

It is the closest thing to a receipt, which is why we carry it beside the fees rather than instead of them. Fees tell you what should happen; tracking difference tells you what did. When the two do not agree, the gap is the interesting part — and a fund whose costs do not explain its tracking is flagged here rather than smoothed over.

Where each figure is filed

Nothing on this page requires a data vendor. All of it is filed with the SEC:

• Prospectus — the fee table: management fee, other expenses, acquired fund fees, the gross and net ratios, and the footnote carrying the waiver’s expiry. Also portfolio turnover. This is the document that matters most and the one almost nobody opens.
• Statement of additional information — the detail the prospectus summarises, including brokerage arrangements and securities lending.
• Annual and semi-annual reports — what the fund actually spent, what it distributed, and how it did against its index.
• Portfolio holdings reports — what the fund owns, filed monthly, which is how structure is determined rather than guessed from a name.
• Market data — the spread, and any premium or discount to net asset value.

None of this is a recommendation about any fund, and none of it is tax advice. It is a description of what a cost is and where it is written down.