Tax Loss Harvesting, Explained: A Smart Investor’s Guide

What is tax loss harvesting, exactly? If you’ve heard the term but aren’t sure what it means — or whether it has any relevance for your portfolio — stick with us. In the following guide, we’ll walk through what the strategy is, how it works, the IRS rules to know, and how to decide if it’s right for you.

What Is Tax Loss Harvesting?

Tax loss harvesting is a tax strategy that involves selling investments at a loss to offset capital gains taxes from other investments sold at a profit. Investors use it to reduce their annual tax bill.

Done properly, the strategy can defer taxes and keep a portfolio balanced. Done sloppily, it can trigger IRS penalties. Investopedia’s overview of tax loss harvesting is a useful primer if you’re new to the concept.

How the Strategy Works

Most investors turn to this approach near the end of the tax year. By then, they’ve reviewed how their portfolio performed and how it will affect their taxes.

The mechanics are simple. First, the investor sells one holding that has lost value. Next, the loss offsets a gain elsewhere in the portfolio. Finally, the investor uses the proceeds to buy a similar (but not identical) asset to keep the portfolio balanced.

This strategy only applies to taxable accounts. The IRS doesn’t tax growth inside tax-sheltered accounts, so it makes no sense to harvest losses inside a 401(k), 403(b), IRA, or 529 plan. For one related strategy that does work inside retirement accounts, see our guide to Roth IRA conversions.

What Happens When Losses Exceed Gains

If your annual capital losses are greater than your annual capital gains, you can deduct up to $3,000 in net losses against ordinary income. Married filing separately is capped at $1,500.

If your net losses exceed $3,000, the IRS lets you carry the excess forward into future tax years indefinitely. As a result, a big loss this year can keep working for you long after.

Keeping Your Portfolio Balanced

Selling an asset at a loss disrupts your portfolio’s balance. For this reason, most investors immediately replace the sold asset with something similar. The replacement keeps your expected risk and return in line with your strategy — without violating IRS rules (more on those next).

IRS Rules for Tax Loss Harvesting

Three IRS rules matter most. Get any of them wrong and you forfeit the benefit.

The Wash-Sale Rule

The wash-sale rule is the big one. It prohibits buying the same — or a “substantially identical” — security within 30 days before or after selling it at a loss. That’s a 61-day window total.

If the IRS labels a transaction a wash sale, the loss can’t offset capital gains. IRS Publication 550 has the technical detail. Repeat violators can face penalties.

Short-Term and Long-Term Pairing

Losses are first used to offset gains of the same type. Short-term losses (assets held under a year) offset short-term gains. Long-term losses (assets held over a year) offset long-term gains. Afterward, any leftover losses can offset the other type of gain. IRS Topic 409 covers the full hierarchy.

The December 31 Deadline

All harvesting activity must close by December 31. Don’t make the mistake of thinking you have until the April tax-filing deadline. The IRS offers no leniency on this — the trade has to settle in the current calendar year for it to count.

The Limits of the Strategy

One important caveat: while harvesting losses can lower your current tax bill, it doesn’t eliminate taxes. It defers them.

When you replace an asset with a similar one, your new cost basis is lower than the original. As a result, when you eventually sell that replacement at a gain, the taxable gain will be larger. The strategy is most valuable when your future tax rate will be lower than your current rate, or when you can carry losses forward indefinitely.

Is Tax Loss Harvesting Right for You?

Tax loss harvesting can be powerful, but it isn’t right for everyone. The strategy makes the most sense if you have:

• A taxable brokerage account with realized or unrealized gains
• A diversified portfolio that allows for clean replacement assets
• A high enough marginal tax rate that the deferral is meaningful
• Patience and discipline to follow the wash-sale rules

If you’re wondering whether the strategy fits your situation, we recommend speaking with a qualified tax professional. The right move depends on your portfolio, your tax bracket, and your long-term financial goals. For more on year-end planning, see our guide on when to meet with your accountant.

Get Help Building a Smarter Tax Strategy

The tax experts at Honest Buck help individuals and business owners build tax and investment strategies that actually pay off. Schedule a call with us today to learn more.