To invest in the USA, you need a U.S. taxpayer identification number, the correct residency form on file with your broker (W-9 if you’re a U.S. person, W-8BEN if you’re not), and an account at a brokerage registered with the SEC and covered by SIPC. Everything after that — what you’re taxed on, how much is withheld, what you have to report — turns on whether you’re investing as a U.S. citizen or resident, or from abroad.
What You Need Before You Open an Account
Every U.S. brokerage account starts with a taxpayer identification number. U.S. citizens and permanent residents use a Social Security Number.1Internal Revenue Service. Taxpayer Identification Numbers (TIN) If you aren’t eligible for an SSN, you apply for an Individual Taxpayer Identification Number by filing Form W-7 with the IRS.2Internal Revenue Service. About Form W-7 Processing runs about seven weeks under normal conditions and nine to eleven weeks if you file between mid-January and the end of April, or from overseas.3Internal Revenue Service. Form W-7 (Rev. December 2024) Build that wait into your timeline.
With the number in hand, the brokerage will ask for one of two forms.
W-9 for U.S. Citizens and Residents
The W-9 puts your legal name and taxpayer ID on record and certifies that you’re not subject to backup withholding.4Internal Revenue Service. About Form W-9 The name on line 1 has to match the name on your federal tax return. Skip this form or give incorrect information and the brokerage withholds 24% on all your dividends, interest, and other reportable payments.5Internal Revenue Service. Instructions for the Requester of Form W-9
W-8BEN for Non-Resident Aliens
If you’re not a U.S. person, you file a W-8BEN instead. This form establishes your foreign status and, if a tax treaty applies between your country and the U.S., lets the broker reduce the withholding rate on your dividends.6Internal Revenue Service. About Form W-8 BEN Part II is where you name your country of residence and cite the treaty article you’re claiming.7Internal Revenue Service. Form W-8BEN (Rev. October 2021)
A W-8BEN expires on the last day of the third calendar year after you sign it. A form signed in March 2026 expires December 31, 2029. Let it lapse and the broker reverts to the full 30% withholding rate on everything paid to you thereafter.8Internal Revenue Service. Instructions for Form W-8BEN (10/2021) Put the renewal date in your calendar the day you sign.
Choosing a Brokerage
Broker-dealers execute your trades. Full-service firms bundle research and planning with execution and typically charge a percentage of assets under management. Discount and online brokerages give you a self-directed platform, and many now charge zero commission on stock and ETF trades. Both types must register with the SEC and join FINRA, which sets capital and fair-dealing standards.9U.S. Securities and Exchange Commission. Guide to Broker-Dealer Registration
If a FINRA-member broker fails, the Securities Investor Protection Corporation covers up to $500,000 per customer in missing securities and cash, with a $250,000 sublimit on cash. SIPC covers the custody function only; it does not reimburse market losses or bad advice.10SIPC. What SIPC Protects Before signing, read the fee schedule for wire transfers, account maintenance, and paper statements, and expect to answer questions about your income, net worth, and experience — federal suitability rules require the firm to assess whether products like options and margin are appropriate for you.
Opening, Funding, and Placing Trades
Most brokerages handle everything online. You upload your W-9 or W-8BEN, enter your personal details, agree to the customer agreement, and sign digitally. The firm then runs a Know Your Customer identity review, which usually takes two to five business days. You may be asked for additional documents.
To fund the account from a U.S. bank, use an ACH transfer with your bank’s routing and account numbers; it clears in one to three business days. From abroad, use a wire transfer with the SWIFT code and credit instructions listed on the broker’s funding page.
Stock and ETF trades settle the next business day under the SEC’s T+1 rule, in effect since May 2024.11Investor.gov. New T+1 Settlement Cycle Buy on Monday, the shares are in your account Tuesday; sell on Monday, cash is available Tuesday.
What You Can Buy
The three core building blocks in a standard brokerage account are individual stocks (ownership in a company), exchange-traded funds (a basket of securities trading as a single fund throughout the day), and U.S. Treasury securities — short-term Bills, medium-term Notes, and long-term Bonds issued by the federal government.12TreasuryDirect. About Treasury Marketable Securities
Tax-Advantaged Retirement Accounts
If you have U.S. taxable compensation, you can shelter investment gains inside a retirement account. For 2026, the employee 401(k) contribution limit is $24,500, with an $8,000 catch-up at age 50 and $11,250 for workers aged 60 through 63.13Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026 The IRA limit is $7,500 for 2026, plus $1,100 catch-up at 50 or older.14Internal Revenue Service. Retirement Topics – IRA Contribution Limits
A traditional IRA gives you a deduction now and taxes withdrawals in retirement. A Roth IRA runs in reverse: no deduction today, tax-free qualified withdrawals later. Roth contributions phase out at higher incomes; for 2026 the range is $153,000 to $168,000 for single filers and $242,000 to $252,000 for married joint filers.13Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026 Overcontribute and you owe a 6% excise tax on the excess every year it stays in the account.14Internal Revenue Service. Retirement Topics – IRA Contribution Limits
How Your Gains and Dividends Are Taxed as a U.S. Investor
Hold an investment more than a year before selling and any profit is a long-term capital gain, taxed at preferential rates. Sell within a year and it’s a short-term gain, taxed as ordinary income at rates as high as 37% for 2026.15Internal Revenue Service. Topic No. 409, Capital Gains and Losses
For 2026, single filers pay:
- 0% on taxable income up to $49,450
- 15% from $49,451 to $545,500
- 20% above $545,500
For married couples filing jointly, the 0% rate runs up to $98,900, 15% covers $98,901 to $613,700, and 20% applies above $613,700.16Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
Qualified dividends get the same preferential long-term capital gains rates. Ordinary (non-qualified) dividends are taxed at your regular income rate. Unlike non-residents, U.S. investors generally pay dividend tax through their annual return rather than through withholding at the source.
The 3.8% Net Investment Income Tax
Higher-income U.S. residents owe an extra 3.8% surtax on net investment income — capital gains, dividends, interest, rental income, and certain royalties. It applies to the lesser of your net investment income or the amount by which your modified adjusted gross income exceeds $200,000 (single or head of household), $250,000 (married filing jointly), or $125,000 (married filing separately).17Internal Revenue Service. Topic No. 559, Net Investment Income Tax These thresholds aren’t indexed to inflation, so more filers cross them each year. NIIT does not apply to non-resident aliens.
How Your Gains and Dividends Are Taxed if You Invest From Abroad
The rules flip in ways that favor foreign investors on capital gains and hit them hard on dividends.
Capital Gains and the 183-Day Rule
A non-resident alien who is physically present in the United States for fewer than 183 days during the tax year generally owes no U.S. tax on gains from selling stocks, ETFs, or other capital assets.18Office of the Law Revision Counsel. 26 USC 871 – Tax on Nonresident Alien Individuals Cross 183 days and those gains face a flat 30% tax on the net amount. This is why many foreign investors can trade U.S. securities from home with no federal capital gains liability. Track your days carefully; miscounting turns a tax-free gain into a heavily taxed one.
Dividend Withholding and Treaty Rates
Dividends paid by U.S. companies to non-resident aliens are subject to a default 30% withholding tax, deducted by the broker before the money reaches you.19Internal Revenue Service. NRA Withholding The U.S. has tax treaties with dozens of countries that lower that rate, often to 15%, but only if you have a current W-8BEN on file.20Internal Revenue Service. Federal Income Tax Withholding and Reporting on Other Kinds of U.S. Source Income Paid to Nonresident Aliens
A few common portfolio-dividend rates from IRS Treaty Table 1:
- Canada: 15%
- United Kingdom: 15%
- Japan: 10%
Corporate shareholders with large ownership stakes may qualify for lower rates under the same treaties.21IRS. Table 1 – Tax Rates on Income Other Than Personal Service Income Under Chapter 3 No treaty means the full 30% comes off every dividend.
Real Estate: The FIRPTA Boundary
Real estate lives in a separate withholding regime. When a foreign person sells a U.S. real property interest, the Foreign Investment in Real Property Tax Act requires the buyer to withhold 15% of the total sale price and send it to the IRS as a prepayment of the seller’s income tax.22Office of the Law Revision Counsel. 26 USC 1445 The rate drops to 10% for personal residences selling at $1,000,000 or less. If the withholding is more than your actual tax on the gain, you can file Form 8288-B in advance to reduce it.23Internal Revenue Service. Reporting and Paying Tax on U.S. Real Property Interests Title companies enforce FIRPTA strictly because the buyer is on the hook if it’s skipped.
The Estate Tax Trap for Non-Residents
Non-resident investors often miss this until it’s too late. U.S. citizens and residents get a federal estate tax exemption of $15,000,000 for 2026.24Internal Revenue Service. What’s New – Estate and Gift Tax Non-resident aliens get a credit of just $13,000 under 26 U.S.C. § 2102, which shelters only about $60,000 of U.S.-situated assets.25Office of the Law Revision Counsel. 26 USC 2102 – Credits Against Tax Everything above is taxed at rates up to 40%.
U.S.-situated assets include stocks of U.S. companies, U.S. real property, and cash in U.S. bank accounts (with some exceptions for bank deposits). A non-resident with a $500,000 U.S. stock portfolio could face a substantial estate tax bill at death. Some treaties provide relief by extending a proportional share of the U.S. citizen exemption, but many countries have no such treaty. If yours doesn’t, talk to a cross-border tax advisor before building a large U.S. portfolio.
Reporting Requirements for Cross-Border Accounts
If you’re a U.S. person with accounts outside the United States, two separate filings can apply, and the penalties for ignoring them are steep.
FBAR (FinCEN Form 114)
Any U.S. person with a financial interest in or signature authority over foreign financial accounts must file the Report of Foreign Bank and Financial Accounts if the combined value tops $10,000 at any point in the year.26FinCEN.gov. Report Foreign Bank and Financial Accounts It’s filed electronically with FinCEN — not the IRS — and is due April 15 with an automatic extension to October 15. Civil penalties for non-willful violations can reach $10,000 per account per year; willful violations can run to the greater of $100,000 or 50% of the account balance. Dual citizens and recent immigrants are the most common casualties.
FATCA (Form 8938)
U.S. taxpayers with foreign financial assets above set thresholds also file Form 8938 with their annual return. For filers living in the U.S., that’s $50,000 on the last day of the year or $75,000 at any point during the year (single), doubled for joint filers.27Internal Revenue Service. Do I Need to File Form 8938 Filers living abroad face higher thresholds: $200,000 on the last day or $300,000 at any time for single filers. FBAR and Form 8938 overlap but don’t replace each other. Many taxpayers owe both filings for the same accounts.
Penalties for Getting It Wrong
The IRS charges a failure-to-file penalty of 5% of the unpaid tax for each month a return is late, capped at 25%.28Office of the Law Revision Counsel. 26 USC 6651 A separate failure-to-pay penalty of 0.5% per month runs concurrently, also capped at 25%. Together they can eat a large share of an unpaid balance within a year. Intentional evasion or filing fraudulent forms brings criminal exposure. States often add their own late-filing penalties on investment income sourced within their borders.
Clean records of every trade, dividend, and distribution are the simplest protection. If your situation crosses borders, hire a tax professional who works cross-border returns rather than sorting out treaty provisions and withholding credits alone.