Rebalancing Strategy — When, How, and the Tax You Must Weigh
"Hold to the weights you once set" — advice you've read plenty of times in books, but applying it in practice isn't simple. Monthly vs annual? A 1pp drift vs 5pp? And if you're a Korean resident, you can't ignore the capital-gains tax / dividend income tax that may apply when you sell, depending on the product and account. This article covers four rebalancing strategies and a practical guide for the Korean tax environment.
1. Why rebalancing matters
Rebalancing serves two practical purposes:
- Risk management — keeping the risk level you originally intended. If stocks drift from 60% → 80%, your risk is now higher than you meant it to be.
- Disciplined allocation — trimming assets that have risen and adding to underweight assets helps maintain the target mix. Additional return or alpha is not guaranteed, and trading costs and taxes still matter.
2. Four trigger strategies
| Strategy | Trigger | Pros / cons |
|---|---|---|
| Time-based | Quarterly / semi-annual / once a year | Simple, easy to automate / forces trades regardless of market moves |
| Threshold-based | Weight drift ±5pp | Only when actually needed / frequent trades in big market swings |
| Hybrid | Quarterly check + execute only if ≥5pp | The generally recommended approach / needs monitoring |
| New-cash routing | Buy the lagging assets with monthly contributions / dividends | Can reduce sale-triggered taxes / requires a large enough contribution |
Vanguard's rebalancing guide emphasizes risk control and costs, and describes annual rebalancing as suitable for many investors. A 5pp drift is an example rule, not a universal optimum or a promise of extra return. (Checked 2026-10-04)
3. The tax traps for Korean residents
Scope: checked 2026-10-04, for Korean tax-resident individuals using ordinary taxable brokerage accounts. ISA/pension accounts, corporations, nonresidents, and product-specific exceptions require separate checks.
Domestic stocks
Non-major individual shareholders generally owe no capital-gains tax on exchange-traded sales of Korean-listed stocks. Major shareholders, off-exchange sales, and unlisted stocks have different rules. For transfers from 2026-01-01, the levies on sale proceeds are KOSPI: 0.05% securities transaction tax + 0.15% special tax for rural development = 0.20% total; KOSDAQ: 0.20% securities transaction tax. Brokerage fees are separate. Securities Transaction Tax Act enforcement-decree amendment · Special Tax for Rural Development Act, Article 5
Foreign stocks
For ordinary shares issued by foreign corporations, taxable annual realized net gains above the KRW 2.5 million basic deduction generally face 22% tax (20% capital-gains + 2% local income tax). Eligible taxable domestic and foreign stock gains/losses are netted, with one combined annual KRW 2.5 million deduction; losses on exempt domestic stocks cannot be offset. Check residency requirements too, including continuous Korean residence or domicile for at least five years through the sale date for the foreign-stock rules described here. NTS tax scope and netting guidance · NTS tax rates
ETFs
- Korean-listed domestic-equity ETFs — qualifying funds, such as those tracking domestic stock indexes 1:1, have exempt trading gains. Taxable distributions generally face 15.4% withholding.
- Other Korean-listed ETFs — foreign-index, bond, and commodity funds generally face 15.4% withholding on the smaller taxable amount of the trading gain and increase in tax-base NAV. The stock capital-gains deduction does not apply. Product-specific tax bases and deferred taxable amounts can affect the calculation, including for derivatives-based funds.
- US-listed ETFs (e.g., SPY, VOO) — trading gains generally follow the foreign-stock rules and deduction above. Distributions are taxed separately.
Korean-listed investment-trust ETFs are exempt from securities transaction tax. The 15.4% rate is a general withholding rate; aggregate financial-income taxation and account/product rules can change the final liability. KRX ETF tax guide · NTS financial-income guidance
The annual KRW 2.5 million deduction is a consideration, not a selling limit. Weigh taxes and trading costs against the risk of drifting from your target, and consider new cash or partial rebalancing. Do not automatically postpone necessary risk adjustments just to avoid tax. This is general information, not individualized tax advice.
4. New-cash routing — rebalancing with fewer sales
When a monthly contribution or dividend comes in, allocate it first to the assets whose weight lags the overall target. Without a sale, no capital gain is realized from that sale; taxes on the dividends themselves and purchase costs may still apply.
Example — Target: US 60% / Korea 30% / Bonds 10%, Current: US 70% / Korea 25% / Bonds 5%, monthly contribution KRW 1 million.
- Bonds underweight (-5pp) → KRW 500,000 (50% of the monthly contribution)
- Korea underweight (-5pp) → KRW 500,000 (50% of the monthly contribution)
- US overweight (+10pp) → buy nothing, but also sell nothing
Progress toward the target depends on contribution size and subsequent market moves. This can reduce sale-triggered taxes and trading costs; it does not eliminate every tax.
If the contribution is large enough (monthly ≥ 1% of the portfolio), new-cash routing may help, but it does not guarantee a return to target weights. If contributions are small or the drift is large (10pp+), use threshold-based selling/buying.
5. Monitoring rebalancing in Multifolios
Multifolios provides targetAlloc (target-weight settings) + rebalancing alerts:
- Setup — enter the target weight (%) for each holding / asset class in the holding editor or in a separate setting.
- Alerts — a browser alert when the current weight drifts ±5pp or more from target (e.g., "⚖️ AAPL rebalancing suggested / target 25% → current 32% / overweight 7pp").
- Display — compare target vs actual weight in the asset-allocation chart on the dashboard.
Alerts fire once a day — cutting out noise on high-volatility days.
6. One-line summary
Rebalancing adjusts weights to maintain the intended risk level. Korean residents should check product/account tax treatment and the combined annual KRW 2.5 million stock capital-gains deduction, then compare new-cash routing with the costs of selling.