Rebalancing With New Contributions
Rebalancing With New Contributions
If you are still in the accumulation phase—earning income and adding to your portfolio regularly—you have a powerful rebalancing tool: you can direct new contributions to underweight assets. This method, called "rebalancing via contributions," is the most tax-efficient and often the most cost-free way to maintain your target allocation.
Key takeaways
- Direct new contributions to whichever asset class is currently underweight relative to your target allocation.
- This method is tax-free (in any account type) and cost-free (no trading, no commissions, no spreads).
- It is most effective for investors still accumulating (adding regular contributions from income or savings).
- Combined with dividend reinvestment, directing contributions can often eliminate the need to sell existing positions.
- In taxable accounts, this is often the optimal first step before considering whether selling is necessary.
How rebalancing via contributions works
Suppose you have a 60/40 portfolio (60% equities, 40% bonds) worth €100,000. Equities have surged, and your allocation has drifted to 65/35. You have €5,000 to contribute this month from your salary.
Instead of adding the €5,000 proportionally (€3,250 to equities, €1,750 to bonds), you add the entire €5,000 to bonds. This increases the bond allocation while leaving equities untouched. Over time, these directed contributions bring your allocation back toward the target without any selling.
This is rebalancing, but it is "rebalancing by starving the winner." You are not selling equities; you are just choosing not to buy more of them. Instead, you are buying more bonds, which restores the balance.
Why this matters: it is tax-free and cost-free
In a taxable account, selling an appreciated equity position to raise cash for bonds incurs capital gains tax. The tax friction can consume a significant portion of the rebalancing benefit. By contrast, directing a new contribution to bonds costs nothing—no tax, no commission, no bid-ask spread.
In any account type, directing contributions avoids transaction costs. You are not trading; you are simply choosing where to deploy fresh capital. This is free.
The mechanics
Step 1: Calculate your target allocation. You want 60% equities and 40% bonds.
Step 2: Calculate your current allocation. You are currently 65% equities and 35% bonds.
Step 3: Identify the underweight asset. Bonds are underweight (35% vs. 40% target; a shortfall of 5 percentage points).
Step 4: Direct all contributions to the underweight asset. Direct the €5,000 to bonds.
Step 5: Repeat monthly, quarterly, or as contributions arrive. Each time new money arrives, direct it to whichever asset class is most underweight. Over time, the allocation drifts back to target.
How long does rebalancing via contributions take?
The time horizon depends on the size of your contributions relative to your portfolio and the magnitude of the drift.
Example 1: You have a €100,000 portfolio that has drifted from 60/40 to 65/35. You contribute €1,000 per month. To restore the 40% bond allocation (currently €35,000), you need to add €5,000 to bonds. At €1,000 per month directed entirely to bonds, this takes five months.
Example 2: You have a €500,000 portfolio drifted to 70/30 from a 60/40 target. You contribute €2,000 per month. To restore bonds to 40% (€200,000 total, currently €150,000), you need to add €50,000. At €2,000 per month, this takes 25 months.
In both cases, the drift is corrected through contributions alone, without selling.
Combining contributions and dividend reinvestment
If your portfolio generates dividend income, you can amplify the effect by directing both contributions and dividends to the underweight asset.
Example: Your 60/40 portfolio generates €4,000 in dividends annually and you contribute €12,000 annually. If your portfolio is overweight stocks, you direct the €4,000 dividends and €12,000 contributions to bonds. That is €16,000 per year—€1,333 per month—flowing to the underweight asset. Drift corrects faster.
Many dividend-paying portfolios (especially those heavy in bonds and dividend stocks) generate enough income to rebalance entirely through contributions and dividends, with zero selling.
When contributions are not enough
Contributions work well if:
- You are actively accumulating (adding regularly from income or savings).
- Your contributions are large relative to your portfolio size (so directed contributions meaningfully move the allocation).
- Your portfolio generates sufficient income (dividends, interest) to amplify the effect.
- You can tolerate waiting months or years for drift to correct via contributions.
Contributions do not work if:
- You have stopped accumulating (you are in drawdown or retired).
- Your contributions are tiny relative to your portfolio (€100 per month into a €1 million portfolio moves the needle glacially).
- Your portfolio generates little or no income.
- You have a large drift (say 20% overweight equities) and cannot wait years to correct it.
In these cases, you will eventually need to sell, which is the subject of the next article.
Tax efficiency in taxable accounts
Directing contributions is particularly valuable in taxable accounts because it avoids realising capital gains. In a taxable account with substantial unrealised gains, directing contributions for a year or two can often correct moderate drift without triggering a single capital gains tax bill. This is a powerful advantage over strict calendar-based or threshold-based rebalancing, which may force selling and taxes.
Psychological benefit: enforced discipline
Directing contributions has a psychological benefit: it enforces discipline. When you commit to "send this month's savings to bonds" instead of "add to whichever asset I feel good about," you are removing emotion from the process. This is a form of automatic rebalancing that requires no decision-making.
The catch: what if your portfolio shrinks?
If you are taking withdrawals from your portfolio (in retirement), rebalancing via contributions does not apply. You cannot "direct new contributions" if there are none. Instead, you can rebalance via withdrawals or sales, which is covered in later articles.
Contribution-based rebalancing example
Next
Contributions and dividends are the first line of rebalancing defence. But they do not always suffice. When contributions cannot close the gap—when you are retired, your portfolio is stagnant, or drift is large—you must rebalance by selling. The next article covers this scenario: how to decide what to sell and how to minimise the tax impact.