Investment Income Tax in the U.S.: Why the Type of Income Determines Your Tax Bill

When you invest in the United States, your money can work through a wide range of financial institutions: mutual funds, money market funds, exchange-traded funds (ETFs), banks, and brokerage accounts. Each of these vehicles earns money in its own way — and, most importantly for a taxpayer, the type of income you receive directly determines how much tax you will pay.

The U.S. investment income tax system works in such a way that the same dollar of income can be taxed at 37%, at 15% — or not taxed at all. The difference lies in how that dollar was earned. Let's break it down.

Who Can Manage Your Money and How the Income Is Generated

Banks and Deposit Accounts

The simplest option: savings accounts, certificates of deposit (CDs), and high-yield savings accounts. The bank pays you interest for the use of your money.

How the income is generated: the bank lends your money out and earns the spread between rates, paying you a fixed or variable interest rate.

Taxation: interest is ordinary income. It is taxed under your regular progressive tax brackets — from 10% to 37% in 2026. The bank will send you Form 1099-INT if your interest for the year is $10 or more. There are no preferential rates for bank interest.

Money Market Funds

Don't confuse these with bank money market accounts. A money market fund is a mutual fund that invests in short-term debt instruments: Treasury bills (T-bills), commercial paper, and short-term municipal bonds.

How the income is generated: the fund earns interest on these securities and distributes it to shareholders — typically on a monthly basis.

Taxation: here's where the confusion begins. Payouts from a money market fund arrive as dividends (Form 1099-DIV), but in substance they are interest income, so they are almost always ordinary (non-qualified) dividends — taxed at your regular rate (10–37%). There are some pleasant exceptions:

• If the fund invests in U.S. Treasury securities, part of the income may be exempt from state income tax.

• If it is a municipal money market fund, the income may be exempt from federal tax entirely (and sometimes from state tax as well, if the bonds were issued by your state).

Mutual Funds and ETFs

A mutual fund pools money from thousands of investors and invests it in stocks, bonds, or a combination of both, under the direction of a professional manager.

How an investor's income is generated — through three channels:

1. Dividends — the fund receives dividends from the stocks (or interest from the bonds) in its portfolio and passes them on to you.

2. Capital gain distributions — the fund manager sold securities inside the fund at a profit, and the fund is required to distribute that profit to shareholders. Important: you can receive such a distribution and owe tax on it even if you sold nothing yourself — and even if the fund's share price dropped during the year.

3. Profit from selling your shares — you sold your fund shares for more than you paid for them.

Each of these income streams is taxed differently — more on that below.

Brokerage Accounts and Individual Stocks

If you buy stocks directly through a broker, you receive dividends from companies and capital gains when you sell. The rules are the same as for funds, but you have more control: you decide when to sell and realize a gain.

Three Kinds of "Dividends" — Three Different Tax Treatments

When Form 1099-DIV arrives in late January, it contains several key boxes. Let's look at the three most important ones.

1. Ordinary Dividends — Box 1a

This is the total amount of all dividend payments for the year. A portion of it may be "qualified" (see below), while the rest is taxed as ordinary income — at your marginal rate of 10% to 37%.

Typical sources of non-qualified dividends: money market funds, bond funds, REITs (real estate investment trusts), and dividends on stocks you held for too short a period.

2. Qualified Dividends — Box 1b

This is the "privileged" portion of your dividends, taxed at the preferential long-term capital gains rates: 0%, 15%, or 20% instead of ordinary rates of up to 37%.

For a dividend to be qualified, certain conditions must be met:

• The dividend must be paid by a U.S. corporation or a qualified foreign company;

• You must have held the stock for more than 60 days during the 121-day period that begins 60 days before the ex-dividend date (for funds, this rule applies both to the fund itself and to you as a shareholder).

Qualified dividend tax rates for 2026 (based on taxable income):

Rate	Single	Married Filing Jointly
0%	up to $49,450	up to $98,900
15%	$49,450 – $545,500	$98,900 – $613,700
20%	over $545,500	over $613,700

Feel the difference: a high-income investor pays 37% on ordinary dividends but only 20% on qualified ones. And a married couple with taxable income up to $98,900 pays nothing at all on qualified dividends.

3. Non-Dividend Distributions — Box 3

Sometimes a fund or company pays you money that is not income at all — it is a return of capital. Essentially, you are getting back a portion of your own invested money.

The tax treatment here is special:

• At the time you receive it, the payment is not taxable;

• However, it reduces your cost basis in the investment. If you bought a share for $1,000 and received $100 as a return of capital, your basis is now $900;

• When you eventually sell the investment, your capital gain is calculated from the reduced basis — meaning the tax doesn't disappear, it is deferred;

• If total returns of capital exceed your basis (your basis reaches zero), any excess is taxed as a capital gain in the year you receive it.

Such distributions are common with REITs, MLPs, and certain funds. Keep careful track of your cost basis — otherwise you may overpay tax when you sell.

Capital Gains: Short-Term vs. Long-Term

When you sell fund shares, stocks, or other assets:

• Held for one year or less → short-term capital gain → taxed as ordinary income (up to 37%);

• Held for more than one year → long-term capital gain → preferential rates of 0% / 15% / 20% (the same thresholds as for qualified dividends).

Capital gain distributions from mutual funds (Form 1099-DIV, Box 2a) are almost always treated as long-term — regardless of how long you have owned the fund shares themselves.

Don't Forget the NIIT — an Extra 3.8%

High-income investors pay the Net Investment Income Tax — an additional 3.8% tax on net investment income (interest, dividends, capital gains) if their modified adjusted gross income (MAGI) exceeds:

• $200,000 — for single filers;

• $250,000 — for married couples filing jointly.

These thresholds are not indexed for inflation, so more taxpayers fall under the NIIT every year.

Investment Income Tax at a Glance: Summary Table

Income Source	Type of Income	Tax Rate (2026)
Bank deposit, CD	Interest (1099-INT)	Ordinary brackets 10–37%
Money market fund	Ordinary dividends	Ordinary brackets 10–37%
Municipal money market fund	Exempt interest	0% federal
Stocks / stock funds (long holding period)	Qualified dividends	0% / 15% / 20%
Bond funds, REITs	Ordinary dividends	Ordinary brackets 10–37%
Return of capital	Non-dividend distribution	0% now (reduces basis)
Asset sold after ≤ 1 year	Short-term capital gain	Ordinary brackets 10–37%
Asset sold after > 1 year	Long-term capital gain	0% / 15% / 20%
High income (MAGI > $200K/$250K)	+ NIIT	+ 3.8% on top

How to Reduce Your Investment Income Tax: Practical Takeaways

1. Look beyond the yield — consider tax efficiency. A fund yielding 5% that pays ordinary dividends may leave you with less after taxes than a fund yielding 4.5% that pays qualified dividends.

2. Practice smart asset location. Bond funds and REITs, which generate ordinary income, are better held in retirement accounts (IRA, 401(k)), where current distributions are not taxed. Stocks paying qualified dividends belong in a regular brokerage account.

3. Hold assets for more than a year whenever possible — the difference between 37% and 15% on substantial amounts is enormous.

4. Review your 1099-DIV carefully. Boxes 1a, 1b, 2a, and 3 represent very different tax fates for the same money.

5. Track your cost basis whenever you receive returns of capital.