Rebalancing After You Stop Contributing
A portfolio that is never rebalanced does not stay where you put it. Strong years in shares raise their weight, so the mix drifts steadily toward more risk — and it drifts furthest just before the falls that punish it. Rebalancing is the correction, and in retirement there is a way to do most of it without a tax bill.
- Drift compounds:: Left alone, a portfolio becomes progressively more concentrated in whatever has risen.
- Two triggers:: Calendar-based, at a set frequency, or threshold-based, when a weight moves beyond a band.
- It is risk control, not return chasing:: The point is keeping the risk you chose, not improving returns.
- Withdrawals rebalance for free:: Taking each year's spending from whatever is overweight moves the mix back with no extra trades.
Where the AI summary above gets this wrong
"Rebalance your portfolio every year to improve returns."
That's surface-true. Here's what it misses:
- Rebalancing controls risk rather than raising returns — Selling what has risen to buy what has fallen does not reliably improve returns, and over long stretches of a rising equity market it reduces them. What it does is keep the portfolio's risk at the level chosen, which matters most in the years before and after retiring.
- Doing it in a taxable account has a cost the plan should account for — Rebalancing inside an IRA or 401(k) is free of tax. Doing the same trade in a taxable account realises capital gains. The order to work in is therefore: adjust inside tax-sheltered accounts first, use withdrawals and new cash next, and sell in the taxable account only for what remains.
- Withdrawals are the retiree's rebalancing tool — Someone drawing income each year has a mechanism a saver does not: take the money from whatever is above its target weight. Over a retirement that alone keeps a portfolio close to its allocation, with no separate trades and no gains realised beyond what was being spent anyway.
01 Why portfolios drift
A portfolio set at a mix of shares and bonds does not hold that mix. In a period when shares outperform, their weight rises, and nothing brings it back automatically. After a long run, an allocation chosen as moderate can be sitting well above it.
The problem is not the higher return that produced the drift. It is that the risk has increased without a decision, and it has increased most after the longest rises — which is precisely when a fall is being least anticipated.
For a household near retirement, that timing is the whole issue. The sequence of returns problem is at its worst in the first years of drawing income, and arriving at that point with an unintentionally aggressive portfolio is the avoidable version of it.
Shows: how much of the portfolio sits away from its target allocation, which is the amount a rebalancing trade would move. Ignores: the tax on realising gains to do it, which account the trade happens in, transaction costs, and whether the target itself is still the right one.
Source: Diversification
02 When to do it
Two approaches are standard. Calendar rebalancing checks at a set frequency — annually is common — and restores the target. Threshold rebalancing acts only when a holding drifts beyond a band, say five percentage points either side of its target.
Neither is clearly better, and both beat the alternative of acting on how the market feels. What matters more is that the rule is written down in advance, because the moment rebalancing is hardest to do is exactly the moment it is most valuable — selling what has been rising, or buying what has fallen.
Combining them works well: check annually, act only if something is outside its band. That keeps the number of trades low and avoids adjusting for trivial movements.
Source: Rebalancing
03 Doing it without a tax bill
Trades inside an IRA or 401(k) produce no tax at all, so the first move is always to rebalance there. For many households the tax-sheltered accounts are large enough to restore the whole allocation on their own.
Next comes cash flow. Every withdrawal is an opportunity: take the year's spending from whichever holding is above its target weight, and the mix moves back without any separate trade. Dividends and interest can be directed the same way rather than reinvested automatically.
Only what remains needs a sale in the taxable account, and there the lot selection rules decide the cost — identifying high-basis lots keeps the realised gain small. Done in that order, most retirement rebalancing costs nothing in tax at all.
Source: Asset allocation
The rebalancing conversation is never about the mechanics. It is about the fact that selling the thing that has done well feels wrong, every single time, and buying the thing that has fallen feels worse. That is why the rule has to be written down in a calm year. Mine is simple: check every January, act only if something is more than five points off, and take that year's spending from whatever is highest. Most years there is nothing else to do.
FAQ
How often should I rebalance?
Annually is a reasonable default, or whenever a holding drifts beyond a set band such as five percentage points. What matters most is having a rule written down before the market makes it difficult to follow.
Does rebalancing improve returns?
Not reliably. It controls risk by keeping the portfolio at the allocation you chose. Over a long rising equity market it can reduce returns slightly, which is the price of not drifting into more risk than intended.
How do I rebalance without triggering tax?
Trade inside tax-sheltered accounts first, then direct withdrawals and dividends away from whatever is overweight. Only the remainder needs a sale in a taxable account.
Sources
Regulator references
- Rebalancing · U.S. Securities and Exchange Commission · 2026What rebalancing does and the two common triggers for doing it.Last verified: 2026-09-07
- Asset allocation · U.S. Securities and Exchange Commission · 2026The target mix that rebalancing restores.Last verified: 2026-09-07
- Diversification · U.S. Securities and Exchange Commission · 2026Why the drifted portfolio carries more concentrated risk than intended.Last verified: 2026-09-07
Calculator unit tests · the assertions this page's worked example is checked against, and their last result
Changelog
- 2026-09-07 — initial publish (new format)
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Jordan Reeves
Founder of Talk Through Wealth. A software engineer for over a decade before turning to retirement planning, Jordan built the projection engine after watching family members get fragmented, country-by-country advice that never reconciled. He writes about retirement the way the engine computes it: month-by-month, lifetime-long, and skeptical of any rule of thumb that hasn't been run through the math.