Sub-Brokerage vs an Overseas Broker: Break-Even Points by Annual Investment and Number of Trades (2026 Official Fees)

The cost difference between sub-brokerage (複委託, a Taiwanese broker placing US orders for you) and an overseas broker comes down to how each one charges: sub-brokerage charges per trade, while overseas brokers mostly charge zero commission but every wire has a fixed cost. Which one is cheaper depends on how much you invest each year, how many trades you make and how many times you wire money, not on whose advertising claims the lowest price.

The short answer: at the official fees checked on 14 October 2026, Cathay and SinoPac charge 0.08% for online sub-brokerage orders with no minimum fee (promotion until 31 December 2026). Against Firstrade’s zero commission plus a LINE Bank wire at NT$150 each, the overseas broker is cheaper once your annual investment exceeds “wires per year × NT$187,500”. For example, if you wire 4 times a year, an overseas broker saves money once you invest more than NT$750,000 a year. For small monthly purchases, a sub-brokerage regular savings plan (Cathay charges US$0.1 per purchase) is actually the cheapest. The tables below work this out for different fee structures, amounts and numbers of trades.

This post is a summary of information, not investment, tax or legal advice, and it does not recommend any broker, individual stock or ETF. The fees were checked against brokers’ and banks’ official pages on 14 October 2026. Promotions expire and fees change, so check each provider’s current notices before you open an account or place an order. The break-even points are inferences from the assumptions in this post, not guarantees.

Sub-brokerage vs an overseas broker: where the costs differ

Both routes require converting NT dollars into U.S. dollars. The differences come in the later stages.

Neither route avoids the currency conversion. Taking the E.SUN Bank posted exchange rates at 13:10 on 14 October 2026 as an example, the spot buying rate for USD was 32.17 and the selling rate 32.27, so converting to U.S. dollars cost about 0.16% of the mid-rate. The calculations in this post assume the spread is the same on both routes and compare only trading fees and wire fees.

Taiwanese sub-brokerage fees: commissions, minimums and transfer-out fees

The table shows each broker’s U.S. stock fees as stated on its official pages, checked on 14 October 2026.

Sub-brokerage fees are mostly written as a “range” or a “discounted rate”. Which one applies to you depends on the terms you signed when opening the account and how you place orders. Three points are easy to miss:

• Promotions have end dates: Cathay’s and SinoPac’s 0.08% both run until 31 December 2026. Cathay’s posted rate is 1%; what it charges after the promotion ends depends on the broker’s notice at that time.
• Settlement remittance fees: if your SinoPac foreign-currency settlement account is not at Bank SinoPac, you pay an extra US$15 on each trade date, about NT$484, which is more than the trading fee itself. Setting up the settlement account at the bank in the same group when you open the account avoids this charge.
• Selling also costs a fee: sub-brokerage charges on both the buy and the sell. Selling an ETF at Cathay is also US$3 per trade, and selling an individual stock is 0.08%.

U.S. market regulatory fees are the same on both routes, such as the SEC fee of 0.00206% on sales (listed on both SinoPac’s and Cathay’s fee pages), so this post leaves them out of the comparison.

Overseas broker fees: Firstrade, IBKR, Schwab and the cost of wiring money

Some limits to know first:

• IBKR Lite’s zero commission is only open to U.S. residents (per IBKR’s commissions page). Taiwan residents open IBKR Pro and pay a commission of at least about US$1 per order.
• Schwab’s pricing guide says “not all products and services are offered in every country”. This post did not find an explicit country list on Schwab’s official pages showing whether Taiwan residents can open Schwab One International, so check this yourself in the application process before applying.
• Schwab charges up to 3% of the principal for currency conversion, so converting to U.S. dollars in Taiwan before wiring is usually simpler than letting the broker convert.

The cost of wiring money: LINE Bank at NT$150 per transfer as an example

The fixed cost of an overseas broker is mainly the wire. This post uses LINE Bank as the example: a transfer to the U.S. costs NT$150 (normally NT$600), and only full-amount delivery is offered, so intermediary banks cannot deduct from it. The promotion runs from 1 January to 31 December 2026 (LINE Bank remittance offer, checked 2026-10-14). When you convert NT dollars to U.S. dollars and send them out, neither a single transfer nor the daily total may reach the equivalent of NT$500,000, so large amounts need to be split over several days, or converted to U.S. dollars first and then sent in that currency.

Traditional banks charge roughly NT$300 to NT$600 per regular wire, and more if you choose full-amount delivery. The bank comparison, Firstrade’s rules on the sender’s name and how much to send at once are covered in The Real Cost of Wiring Money from Taiwan to a U.S. Broker. If you don’t use LINE Bank, just replace NT$150 in the formulas below with your own cost per wire.

Break-even points by annual investment and number of trades

This section is the site’s own calculation. The figures are inferences, not broker announcements.

Assumptions

• Only the cost of buying is counted: sub-brokerage trading fees and settlement remittance fees against the overseas broker’s wire fees. The costs of selling and bringing the money back to Taiwan are covered separately.
• The overseas broker is Firstrade or Schwab (zero commission), and each wire costs NT$150 (LINE Bank). With IBKR Pro, add about US$1 per trade.
• The exchange-rate spread is the same on both routes and is left out.
• U.S. dollars are converted at E.SUN Bank’s spot selling rate of 32.27 on 14 October 2026, so US$3 is about NT$97 and US$15 about NT$484.
• “Number of trades” means how many purchases a year; the overseas broker scenarios assume one wire before every purchase (the most conservative case).

Sub-brokerage at 0.08% vs an overseas broker: annual investment × number of trades

With sub-brokerage at 0.08% and no minimum fee, the year’s fees depend only on the total invested, not on how many purchases it is split into; an overseas broker charges once per wire. Each cell below shows “sub-brokerage cost / overseas broker cost”, followed by the cheaper side.

The larger the amount and the fewer the wires, the better an overseas broker looks; for small amounts bought every month, sub-brokerage costs less. If you buy every month but wire money only once a quarter, use the “4 wires” column for the overseas broker’s cost.

Break-even formulas for other fee structures

Written as formulas: you invest A NT dollars a year, wire W times a year and buy N times a year, and each wire to the overseas broker costs NT$150.

What stands out in the table:

• With ETFs at US$3 per trade, if you wire money before every purchase, sub-brokerage is cheaper (NT$97 is less than NT$150); but as soon as one wire covers two or more purchases, the overseas broker costs less.
• A regular savings plan is the cheapest way to use sub-brokerage. Cathay charges US$0.1 per purchase and Yuanta 0.1%, capped at US$1 per trade, so a year of monthly purchases costs roughly a few dozen to about NT$400 in buying fees.
• The end of the promotions is the biggest unknown. If the 0.08% rate ends and the posted 1% applies again, an overseas broker becomes cheaper as soon as you invest more than NT$15,000 a year with one wire.

The cost of selling and bringing money back to Taiwan

The figures above count only buying. When you sell and take the money back to Taiwan:

• Sub-brokerage also charges a fee on sales (for example Cathay’s 0.08% for individual stocks and US$3 per trade for ETFs), and the money goes straight back to your settlement account.
• Overseas brokers charge no commission on sales (Firstrade, Schwab), but sending the money back to Taiwan costs the broker’s outgoing wire fee: Firstrade charges US$25 per domestic or international wire, and Schwab US$25 per wire or US$15 when requested online (see the broker comparison in The Real Cost of Wiring Money from Taiwan to a U.S. Broker). The receiving bank in Taiwan may also charge an incoming fee.

For long-term holders who rarely sell, the selling cost spread over the years is small; for frequent traders, the sub-brokerage fee on every sale needs to be added to the comparison.

Estate tax, W-8BEN and dividend withholding: the rules on both routes

This section only summarizes official rules and does not assess your personal situation.

U.S. estate tax

The IRS says that when a person who is neither a U.S. resident nor a U.S. citizen dies, a Form 706-NA must be filed if the fair market value of U.S.-situated assets exceeds US$60,000. Shares of U.S. companies are U.S.-situated assets, even if the stock certificates are held outside the U.S. or the shares are registered in the name of a nominee (IRS: Some nonresidents with U.S. assets must file estate tax returns, page updated 2026-06-27).

A common claim online is that “buying through sub-brokerage means no U.S. estate tax”. Sub-brokerage shares are held in the broker’s name at an overseas custodian, but the IRS wording does not exclude shares just because they are registered to a nominee. This post found no official guidance it could cite on how inheritance of sub-brokerage accounts works in practice or whether a filing would be required, so it draws no conclusion. If you hold large assets, ask an accountant or lawyer who knows U.S. estate tax directly.

The fee for inheritance is published, though: SinoPac Securities charges US$100 per stock for a U.S. stock “gift/inheritance transfer to another broker” via DTC.

W-8BEN and dividend withholding

• Overseas broker: you sign a W-8BEN yourself when opening the account, certifying to the broker that you are not a U.S. person. According to the IRS, a W-8BEN generally remains valid from the date of signing until the last day of the third calendar year; for example, one signed on 30 September 2015 stays valid until 31 December 2018 (Instructions for Form W-8BEN). Brokers usually ask you to sign again before it expires.
• Sub-brokerage: the Taiwanese broker handles the identity documents, and tax is likewise withheld before dividends are credited. SinoPac’s and Cathay’s fee pages both state that cash dividends are withheld at 30%; SinoPac also lists US$100 per copy for requesting the previous year’s Form 1042-S.
• Where the 30% comes from: the IRS generally withholds 30% on U.S.-source income paid to foreign persons, which may be reduced only under a tax treaty (IRS: NRA Withholding). The IRS list of tax treaties, checked on 14 October 2026, does not include Taiwan, so dividends are withheld at 30% on both routes.

In other words, there is no difference between sub-brokerage and an overseas broker on dividend withholding.

Differences beyond fees: what you can buy and how to switch brokers

• What you can buy: Yuanta’s operations manual states that under current Taiwanese rules, brokers cannot buy U.S. OTC stocks on a client’s behalf, and not every class of U.S. security can be traded. Overseas brokers generally offer a wider range.
• Limits on regular savings plans: Yuanta’s U.S. stock regular savings plan covers only S&P 500, Nasdaq 100 and Dow Jones 30 constituents and ETFs without leverage or short exposure. Plan holdings are kept separately from ordinary holdings and can only be sold once a day in a batch, without a price limit; moving them to ordinary holdings takes 2 to 3 business days and may incur a transfer fee.
• Cost of switching brokers: moving from sub-brokerage to an overseas broker via DTC costs US$100 per stock at both SinoPac and Cathay, so the more stocks you hold, the more it costs. Deciding on a route from the start saves trouble later.
• Day-to-day use: sub-brokerage can settle in NT dollars, so you never wire money abroad yourself; with an overseas broker you handle the wires, and Firstrade also requires the sender’s name to match the account name exactly.

I have a Firstrade account myself, and I wrote up how I moved RSUs into it from Morgan Stanley in Transferring RSU Shares to Firstrade. Once you have picked a broker, the principles for what to buy and how to hold it are in 10 Principles of Index Investing.

How to use these tables to decide

1. Estimate how much you will invest each year and how many times you will wire money. Someone putting in NT$10,000 a month and buying monthly gets a different answer from someone investing NT$1,000,000 once a year.
2. Check the fee your sub-brokerage account actually pays. Is it the 0.08% promotion, a flat ETF fee or the posted 1%? Is your settlement account at the bank in the same group? When does the promotion end?
3. Apply the formula. At 0.08%, check whether your annual investment exceeds NT$187,500 × wires per year; for a different rate, divide NT$150 by your rate.
4. Think about selling, switching brokers and estate tax together. If you plan to hold for the long term and the amount will keep growing, selling fees and estate tax rules may matter more than a few hundred NT dollars a year in buying costs.

If your money is already at an overseas broker but you are not ready to invest it, see IB01 vs SGOV for the differences between short-term USD Treasury ETFs.

FAQ

Which is cheaper, sub-brokerage or an overseas broker?

It depends on how much you invest each year and how many times you wire money. At the fees checked on 14 October 2026, sub-brokerage online orders cost 0.08% with no minimum fee (Cathay's and SinoPac's promotions run until 31 December 2026). Against Firstrade plus a LINE Bank wire at NT$150 each, the overseas broker is cheaper once your annual investment exceeds 'wires per year × NT$187,500'. This counts buying costs only and assumes the exchange-rate spread is the same on both routes.

For small monthly purchases of U.S. ETFs, should I use sub-brokerage or an overseas broker?

Looking only at buying fees, sub-brokerage regular savings plans are usually cheaper: Cathay charges US$0.1 per purchase in its U.S. stock regular savings plan, and Yuanta charges 0.1% of the trade value, capped at US$1 per trade. Both are less than NT$150 per wire. But regular savings plans only cover certain securities, and Yuanta's regular savings plan holdings can only be sold once a day in a batch, without a price limit.

When do sub-brokerage fee promotions expire?

Cathay Securities' 0.08% for individual stocks and SinoPac Securities' 0.08% for online orders both run until 31 December 2026. Cathay's posted fee rate is 1%, and at SinoPac the part of a month's cumulative trading above US$50,000 is charged at the original rate.

If I buy U.S. stocks through sub-brokerage, do I avoid U.S. estate tax?

Under IRS rules, when a nonresident who is not a U.S. citizen dies, shares of U.S. companies are U.S.-situated assets even if they are registered in the name of a nominee, and U.S. assets above US$60,000 require a Form 706-NA filing. This post found no official source to draw a conclusion on how sub-brokerage accounts are handled in practice, so ask a tax professional.

Do I need a W-8BEN for sub-brokerage? How much tax is withheld on dividends?

When you open an account with an overseas broker, you sign the W-8BEN yourself; it generally stays valid until the end of the third calendar year after signing. On both routes, cash dividends from U.S. stocks are withheld at 30% first, because Taiwan is not on the IRS list of tax treaties. SinoPac's and Cathay's sub-brokerage fee pages also state that dividends are withheld at 30%.

How much does it cost to move sub-brokerage shares to an overseas broker later?

SinoPac Securities and Cathay Securities both charge US$100 per stock to transfer sub-brokerage U.S. shares out via DTC. The more different stocks you hold, the higher the transfer cost.