Tax-loss harvesting—the process of selling off stocks or assets that have dropped in value and taking the losses to offset capital-gains tax liability—is common this time of year as investors look to improve their overall portfolio performance. An article in The Wall Street Journal takes a good look at exactly how valuable this strategy is and how much an investor can add to their returns.

Derek Horstmeyer and Kanwal Ahmad, the authors of the article, ran simulations over various tax regimens, portfolio sizes and holding periods. On average, they found an investor with a potential capital-gains tax rate of 25% could boost their equity portfolio’s annual return by 1.10-1.42% by utilizing tax-loss harvesting.

When the market’s volatile and generating a larger array of loser stocks, the value added could be even greater, the article contends. During a down year, investors can reap the most reward by tax-loss harvesting—up to 3.2% additional return to an equity portfolio with a 25% tax rate. And in years when the S&P 500 was showing more-than-usual volatility, the average investor could gain 2.22% per year.

Of course, the article maintains, tax-loss harvesting is highly personal to each portfolio. Investors looking at high short-term capital gains could benefit even more from tax-loss harvesting since those gains are taxed at a higher rate. And, the authors write, their results are mainly relevant to high-income earners and investors planning to hang onto their winning stocks well into retirement. The results also highlight just how much investors should be paying their managers to utilize the strategy for them: if an asset manager is charging more than 1% of assets, tax-loss harvesting might not be worth it.