01 / HOLDING PERIOD THRESHOLD
Short-Term vs. Long-Term Capital Gains
The single most powerful line in the Internal Revenue Code is 365 days. If you sell an investment held for one year or less, your profit is classified as a Short-Term Capital Gain and taxed at your top marginal ordinary income tax rate (up to 37%). If you hold for at least 366 days, your gain qualifies for preferential Long-Term Capital Gains rates: 0%, 15%, or 20% depending on taxable income. High earners also face the 3.8% Net Investment Income Tax (NIIT) on gains above $200,000 (single) or $250,000 (married).
02 / DIVIDEND CLASSIFICATION
Ordinary vs. Qualified Dividends
Dividends paid to U.S. investors are divided into two distinct categories. Ordinary dividends (which include REIT payouts, bond interest distributions, and short-term fund gains) are taxed as regular earned income. In contrast, Qualified Dividends (paid by domestic or qualifying foreign corporations meeting a 60-day holding period rule) are taxed at preferential long-term capital gains rates (0%, 15%, or 20%), providing significant tax relief in non-retirement accounts.
03 / CAPITAL LOSS WRITE-OFFS
The $3,000 Income Offset
When taxable investments decline, the IRS allows you to turn paper losses into tax deductions. Realized capital losses offset realized capital gains dollar-for-dollar. If total losses exceed total gains in any tax year, up to $3,000 of net investment losses can be deducted directly against ordinary earned W-2 salary income ($1,500 if married filing separately). Any remaining net losses carry forward indefinitely to offset future gains.
04 / THE 61-DAY WINDOW
The Wash-Sale Rule (IRC � 1091)
The IRS prevents investors from selling a stock for a tax deduction and immediately repurchasing it. Under the Wash-Sale Rule, if you sell a security at a loss and acquire a "substantially identical" security within 30 days before or 30 days after the sale date (a 61-day window), your tax loss is disallowed and added to the cost basis of the newly acquired shares. To harvest losses while remaining invested, swap between non-identical index ETFs (such as selling Vanguard VOO and buying Schwab SCHX).
05 / TRIPLE-TAX-SHELTERED
The Health Savings Account (HSA)
If enrolled in a qualifying High Deductible Health Plan (HDHP), the Health Savings Account is the most tax-advantaged account in the U.S. tax code. Contributions are 100% tax-deductible pre-tax (exempt from federal income, state income in most states, and FICA payroll taxes). Balances invest in index funds and compound 100% tax-free. Withdrawals for qualified medical expenses are 100% tax-free at any age. After age 65, non-medical withdrawals function identically to a Traditional IRA.
06 / STATE INCOME TAXES
The Interstate Tax Arbitrage
Federal taxes are only part of the equation. Nine U.S. states levy 0% individual earned income tax (Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, Wyoming). Other states impose progressive rates exceeding 10% (California reaches 13.3%; New York reaches 10.9%). State tax residence substantially alters whether contributing to pre-tax Traditional 401(k)s or post-tax Roth accounts is more advantageous.
