Camille Van Vyve
06 Feb 2026
Capital gains tax: should you rebalance your portfolio annually to benefit from the 10.000€ exemption?
The 10.000€ tax exemption in the context of Belgium’s capital gains tax raises many practical questions for investors. One strategy often mentioned is to rebalance your portfolio annually in order to maximize this exemption. But is this approach truly profitable? An analysis of hidden costs and tax mechanisms reveals a reality that is far more nuanced than it may seem. Let’s take a closer look at the real impact of this strategy on your long-term investments and determine whether it is really worth the effort.
Understanding the tax exemption in the capital gains tax: a 1.000€ benefit, not 10.000€
The 10.000€ exemption on financial capital gains represents a real tax benefit of only 1.000€ per year. This fundamental distinction is crucial: the exemption applies to 10.000€ of capital gains, but the tax actually avoided corresponds to 10% of that amount, i.e. exactly 1.000€.
Rules applicable when selling a portfolio
- In the event of a sale, the capital gain corresponds to the difference between the sale price and the acquisition value. A capital gains tax is applied when this difference is positive, and capital gains that existed before January 1, 2026 are exempt.
- In the case of staggered purchases of the same financial asset, the sale of part of a portfolio follows the FIFO (First In, First Out) method, meaning that the first securities acquired are deemed to be sold first.
- The principle of proportionality also applies, meaning that when a portfolio is partially sold, you sell proportionally part of the initial capital and part of the capital gains.
For example, in a portfolio of 150.000€ made up of 100.000€ in initial capital and 50.000€ in capital gains, a sale of 30.000€ (20% of the portfolio) will proportionally realize 20% of the capital gain, i.e. 10.000€, and 20% of your initial capital, i.e. 20.000€.
The hidden costs of tax-driven rebalancing
Rebalancing a portfolio generates several types of tax and operational costs:
- The stock exchange transaction tax (TOB), which applies to each transaction. It amounts to 0,12% on both purchases and sales for the financial instruments that make up Easyvest portfolios.
- The Reynders tax, which applies to funds and ETFs composed of more than 10% bonds. It amounts to 30% of the gain realized on the bond portion of the fund upon sale.
- The spread, i.e. the difference between the price at which a financial product can be bought and the price at which it can be sold. This varies depending on the financial instruments and market conditions and is around 0,3% for ETFs. However, the effective spread ultimately depends more on market movements between a purchase and a sale.
Numerical analysis: concrete examples for a 200.000€ portfolio
1. Scenario with annual tax-driven rebalancing
Let’s consider an initial portfolio of 200.000€ growing at 8% per year, which is a reasonable long-term average expectation for a global equity index portfolio.
After the first year, the value reaches 216.000€, with 16.000€ in capital gains. To fully benefit from the 10.000€ exemption, it would be necessary to sell the equivalent of 135.000€ of the portfolio (125.000€ of capital + 10.000€ of capital gains) in order to reach the exemption ceiling.
The costs of this operation amount to approximately 729€ (0,3% spread + 0,24% round-trip TOB on 135.000€). The net gain for the first year is therefore only 271€ (1.000€ net exemption – 729€ in costs).
2. Impact over 20 years
In this example, tax-driven rebalancing does not eliminate the entire capital gain. As a result, after 20 years, when the portfolio is liquidated, there remains a capital gains tax of approximately 53.000€ to be paid.
It is also necessary to take into account an annual “friction” linked to TOB and spread costs, as demonstrated above. This tax friction is, however, decreasing over time. Indeed, the higher the capital gain, the larger its proportion within the total capital, and the less of the portfolio needs to be sold in order to benefit from the 10.000€ exemption.
At the beginning, this rebalancing operation is not particularly attractive, as the gain is minimal. After a few years, once capital gains become substantial, it may start to make sense. But in the end, there is still a significant latent capital gains tax remaining.
It should also be noted that selling and immediately repurchasing the same asset solely for the purpose of benefiting from the 10.000€ exemption may be reclassified as tax abuse by the authorities. If this practice does not fall within the scope of normal portfolio management, it could lead to penalties.
3. Scenario without rebalancing: rational simplicity
The passive approach of holding investments without annual rebalancing offers several advantages:
- It eliminates all transaction costs and legal risks.
- It maximizes capital growth by avoiding repeated frictions.
Over 20 years, this simpler strategy generates a higher final capital amount (932.000€ compared to 920.000€), thanks to the annual savings on transaction costs detailed above and the compound interest earned on those savings. The investor thus benefits from optimal compounding of returns.
Although this scenario may seem more attractive at first glance, it is important to consider the net result after taxation. In this case, the tax applied at liquidation is heavier, as it applies to a larger gain that did not benefit from successive exemptions resulting from annual tax-driven rebalancing.
In concrete terms, taxation applies to a capital gain of 732.000€. The net performance after taxes in this second scenario is ultimately 7.480€ lower than in the case with rebalancing. This difference is a far cry from the theoretical 20.000€ (20 × 1.000€) that investors expect when considering an annual tax-driven rebalancing strategy.
Please note that the amounts shown in the charts have been rounded for ease of understanding.
When does rebalancing remain relevant?
The following situations represent legitimate reasons to rebalance a portfolio:
- Correcting allocation drifts between equities and bonds
- Adapting to changes in risk profile
In these cases, capturing the tax exemption represents a welcome secondary benefit. The ETFs selected by Easyvest optimize these operations thanks to their low TOB and reduced spreads.
A rational solution: the income portfolio
The end of both 20-year scenarios corresponds to situations in which the portfolio is fully liquidated. However, income portfolios also exist, allowing capital and capital gains to be used gradually. This approach results in a natural annual tax-driven rebalancing that stems from the receipt of income. To learn more, read our dedicated article on the impact of the capital gains tax on income portfolios.
Conclusion: favor a holistic wealth management approach
The analysis shows that annual rebalancing motivated solely by the 10.000€ exemption generates only a marginal tax advantage relative to the constraints it imposes. With a net gain of just 7.480€ over 20 years, it is fair to question whether this strategy truly justifies the associated effort and risks.
Effective tax optimization is part of a holistic wealth management approach, prioritizing long-term performance over short-term marginal gains. Investors are better served by focusing on building a diversified portfolio aligned with their objectives, while keeping tax considerations in perspective.