How Often Should You Actually Rebalance? The Data Behind the 1-Year Rule
4 min read
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4 min read
You set your portfolio at 70% stocks and 30% gold. A year later stocks have run hard and you are sitting at 80% stocks, 20% gold. You never made that decision. The market made it for you.
Rebalancing is the act of selling some of what grew and buying what lagged, to get back to the split you chose. The question nobody answers well is how often to bother, and the honest answer is: less often than you probably think.
It is not a return-boosting trick. Some years it helps, some years it hurts, and over long periods the return effect is small and unreliable.
What it reliably does is control risk. Left alone, a portfolio drifts toward whatever has been winning, which is usually the most volatile thing you own. That 80/20 split is meaningfully riskier than the 70/30 you signed up for, and you never consciously agreed to the extra risk.
Rebalancing is how you keep the portfolio matching the risk level you decided you could live with. That connects directly to your maximum drawdown: drift quietly deepens the hole you will have to sit through in the next bad quarter.
Here is the side of the ledger people skip.
Every share sale on IDX carries a 0.1% final income tax on gross proceeds, deducted whether or not the trade is profitable. On top of that sit brokerage fees on both the buy and the sell, and VAT on those fees.
| Rebalancing frequency | Sale events per year | Final tax alone, on 20% of a Rp 500,000,000 portfolio |
|---|---|---|
| Annually | 1 | Rp 100,000 |
| Quarterly | 4 | Rp 400,000 |
| Monthly | 12 | Rp 1,200,000 |
The final tax is the floor, not the total. Add brokerage and VAT and monthly rebalancing on that portfolio can comfortably cost several million rupiah a year, to correct drift that would largely have corrected itself.
Calendar rebalancing. Pick a date and check once a year. Simple, requires no monitoring, and hard to talk yourself out of. Annual is the common recommendation precisely because it captures most of the risk-control benefit while keeping trade count near the minimum.
Threshold rebalancing. Only act when an allocation drifts past a set band, commonly five percentage points for a major sleeve. So a 70% stock target triggers at 75% or 65%, and does nothing in between.
Threshold tends to be slightly more efficient because it acts when there is something worth acting on, rather than on a date that has no relationship to what markets did. The cost is that you have to actually check.
Doing both works well: look once a year, and only trade if something has drifted past its band. Many years that means looking and doing nothing, which is a legitimate and often correct outcome.
If you add money regularly, you have a better tool than selling.
Direct new contributions into whatever is underweight. You reach the same target allocation without triggering a single sale, which means no 0.1% final tax and no sell-side fees. You are rebalancing with the money coming in rather than the money already invested.
For anyone still in the accumulation phase and buying monthly, this handles most drift on its own. Selling to rebalance then becomes a rare event reserved for genuinely large gaps.
The same logic applies to assets that are not shares. Metals and manual assets do not incur the IDX sale tax, but they carry their own spreads, and the principle holds: adjust with inflows where you can.
Three cases justify breaking the annual habit.
A very large move. A sleeve that has doubled or halved has changed your risk profile materially and should not wait for a calendar date.
A change in your own circumstances. Approaching a goal, or a change in income stability, can change the allocation you want. That is a re-decision, not a rebalance.
Tax-advantaged accounts, where selling does not trigger the same costs. The cost argument weakens considerably when the toll is not being charged.
Open the Holdings page. It shows your current split across Growth Engine, Inflation Hedge and Bedrock, with a composition bar for each section, so you can see at a glance how far each sleeve has wandered from where you put it.
Compare that against the allocation you actually intended. If nothing has moved more than about five points, the correct action is usually none. If something has, the cheapest fix is to point your next few contributions at whatever is underweight, and only reach for a sale if the gap is too big for inflows to close.