Capital Gains Tax Applies to the Gain, Not the Entire Sale

April arrives, and the brokerage's 1099-B lists every sale you made last year, proceeds and all. Breathe — capital gains tax wants a share of the profit, not of the whole check.

Capital gains tax is the federal tax on realized profits from selling capital assets. The taxable amount is the sale price minus your adjusted basis — what you paid, adjusted for things like commissions and reinvested distributions.

Gain first, then tax

Sell shares with a $15,000 basis for $20,000 and the gain is $5,000; the other $15,000 is your own money coming back. No sale, no tax: an asset that merely rose in value creates no current bill in a taxable account.

Short-term vs. long-term

Hold for more than one year and the gain is long-term, taxed at federal rates of 0%, 15%, or 20% depending on your taxable income. Hold for a year or less and it's short-term, taxed at the same rates as your wages.

That gap is the whole reason careful sellers watch their purchase dates. High earners can also owe an extra 3.8% net investment income tax on top of either rate.

Losses shrink the bill

A realized capital loss offsets gains before any tax is figured — short-term against short-term, long-term against long-term, then whatever's left crosses over. Up to $3,000 of surplus losses can offset ordinary income each year, and the rest carries forward.

That netting makes the tax a portfolio-level calculation, not a per-trade toll. One December sale can change the whole year's answer.

Where the tax works differently

Sales inside IRAs and 401(k)s don't trigger current capital gains tax — those accounts follow their own contribution and withdrawal rules. That's why asset location matters as much as asset choice for taxable investors.

Special regimes sit alongside the basic rates. Home sellers can often exclude up to $250,000 of gain ($500,000 for joint filers), collectibles can be taxed at up to 28%, and most states stack their own income tax on top.

Planning around it, legally

Holding past the one-year line, harvesting losses, and putting tax-heavy assets in sheltered accounts are the standard levers — there's more in strategies to reduce your tax burden. The current rates and rules live in the IRS's Topic 409 on capital gains and losses.

Check the purchase date before you sell a winner — one more month of holding sometimes pays better than the trade did.