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Strategies

Chapter 12: Tax-Loss Harvesting Basics

Pomegra Learn

Chapter 12: Tax-Loss Harvesting Basics

Tax-loss harvesting is one of the few genuinely free tax moves available to individual investors. When you sell a security below your cost basis, you crystallize a capital loss that the IRS allows you to deduct against capital gains and ordinary income. Unlike other tax strategies that require complex legal structures or questionable interpretation, harvesting is straightforward: sell a loser, claim the deduction, and maintain your target allocation by buying a similar (but not identical) replacement fund. If executed correctly, harvesting is a mechanical tax win. If botched, it can trigger audits and penalties.

This chapter walks through the mechanics, the rules, and the decision-making framework. We begin with why the strategy works, move through the US wash-sale rule and its UK counterpart (bed and breakfasting), and address the common misconceptions that lead investors astray. We then examine when harvesting is worthwhile and when it is not—because for many investors and in many situations, the administrative burden is not justified by the tax savings.

The core truth about harvesting: it does not create wealth from nothing. It recovers a percentage of your economic loss in the form of a tax deduction. A $10,000 loss harvested by an investor in the 24% tax bracket saves $2,400 in federal tax. You are still $7,600 worse off overall. The strategy is damage salvage, not a windfall. But if you have high income, significant gains, and a sizable taxable account, the savings compound meaningfully over decades.

What's in this chapter​

How to read it​

Start with "What Is Tax-Loss Harvesting?" to understand the concept and when it makes sense. The next four articles (mechanics, wash-sale rule, bed and breakfasting, and substitute funds) cover the foundational rules you must know to execute correctly.

If you are in the US, pay close attention to the wash-sale rule and the 30-day window; violations are a common and expensive mistake. If you are in the UK, "Bed and Breakfasting" is your equivalent rule and has slightly different mechanics.

"TLH and Portfolio Construction" shows how to integrate harvesting into a broader portfolio design so that it becomes automatic and less error-prone. "When TLH Is Worthless" is equally important: it clarifies the conditions under which harvesting does not pay. Not every investor with losses should harvest them.

The final two articles address edge cases: the precise calendar mechanics of the 30-day window (critical for avoiding wash-sale violations) and why tax-deferred retirement accounts cannot generate harvestable losses.

Read the chapter sequentially if you are building a harvest-ready portfolio for the first time. If you already harvest and are seeking clarification on a specific rule (e.g., wash sales, UK compliance), jump to the relevant section. All articles stand alone but reference each other; follow the "Related concepts" links to deepen your understanding of interconnected topics.

Harvesting is a low-risk, high-reward strategy for the right investor. But it is only appropriate if you are willing to learn the rules and discipline yourself to follow them. If you are prone to second-guessing your allocation or chasing performance, harvesting will add complexity without benefit. If you are a systematic, long-term investor with a substantial taxable account and stable high income, it is a tool worth mastering.