A Capital Loss Turns a Decline Into a Completed Result

The sell order fills at $41.20, eleven dollars under what you paid, and the red number on your screen finally stops moving. That click did something the falling price never could: it turned a bad month into a capital loss.

A capital loss happens when you sell a capital asset — stock, fund shares, crypto, property — for less than your adjusted cost basis. Until you sell, a drop is only an unrealized loss: painful to look at, but not final.

Capital loss at a glance

• The loss is measured against your adjusted basis (what you paid, with adjustments), not against the peak price.
• It becomes real — "realized" — only when you sell.
• Realized losses offset capital gains first, then up to $3,000 of ordinary income per year under current IRS rules.
• The wash-sale rule can postpone the deduction if you rebuy too soon.

How the math works

Say you bought shares for $12,000 and sold them for $9,000. Your realized capital loss is $3,000 — the $9,000 you received is proceeds, not the size of the loss.

If you're still holding at a $9,000 value, nothing's realized yet. The position can recover or keep falling, which is why market risk deserves your attention before the trade, not after it.

How losses offset gains

On your tax return, losses first cancel capital gains of the same type — short-term against short-term, long-term against long-term. Whatever's left over crosses to the other type.

If losses still remain after all that netting, you can deduct up to $3,000 a year against ordinary income ($1,500 if married filing separately). Anything beyond that carries forward to future years and doesn't expire.

The wash-sale rule

Sell at a loss and buy the same or a "substantially identical" security within 30 days before or after, and the IRS disallows the deduction for now. The blocked loss gets added to your new position's basis, so it's deferred, not destroyed.

The rule reaches across your accounts, IRAs included. Waiting out the window — or buying something similar but not identical — keeps the deduction alive.

Tax-loss harvesting

Some investors sell losers on purpose near year-end to bank losses against gains they've already realized — that's tax-loss harvesting. It works best when the sale also fits your plan, like trimming a position you'd already outgrown in your portfolio.

Don't expect the deduction to make you whole, though. Saving taxes on a $3,000 loss hands back a fraction of it; the rest is simply gone.

When taking the loss makes sense

A realized loss isn't automatically a mistake — sometimes it's controlled risk doing its job inside a diversified plan. The real error is sizing a position without knowing how much you could afford to lose.

For current federal guidance, start with the IRS's Topic 409 on capital gains and losses.

Before you sell anything just for the deduction, check the calendar against the wash-sale window first.