Portfolio Rebalancing: Calendar-Based vs Threshold-Based Strategies

Quick answer: Calendar-based rebalancing means you reset your portfolio to its target asset allocation on a fixed date, such as once a year. Threshold-based rebalancing means you act only when an asset class drifts past a set limit, such as 5 percentage points. Calendar is simpler. Threshold reacts better to real market moves. Most Indian investors do best with a mix of both: review on a schedule, trade only when the drift is large enough to matter.

If you hold a mix of equity mutual funds, debt funds and gold, your portfolio does not stay the way you built it. Equity runs ahead in a good year. Debt catches up in a bad one. Over a few years, the 60:40 portfolio you planned can quietly turn into 75:25, and you end up carrying far more risk than you agreed to take.

Portfolio rebalancing fixes this. The real question is when to do it. This guide compares the two most common answers, calendar-based and threshold-based rebalancing, with worked numbers, Indian tax rules, and a clear way to pick between them.

What is portfolio rebalancing?

Portfolio rebalancing is the process of bringing your investments back to your target asset allocation after market movements have pushed them away from it. You do it by selling some of what has grown too large and buying more of what has fallen behind, or by pointing new money at the smaller part of the portfolio.

Say your plan is 60% equity and 40% debt. A strong equity year leaves you at 66% equity and 34% debt. Rebalancing moves you back to 60:40.

Notice what this does. It forces a mild “sell high, buy low” habit without needing a market forecast. It also keeps your risk level where you decided it should be, which matters more than most people realise when markets turn.

Why does a portfolio drift in the first place?

Different assets earn different returns, so their weights change on their own. No one has to make a mistake for drift to happen. It is simply what arithmetic does to a portfolio over time.

Here is a small example. You start with ₹10 lakh split as ₹6 lakh in a Nifty 50 index fund and ₹4 lakh in a debt fund. Over one year, the equity fund rises 20% and the debt fund rises 7%.

• Equity: ₹6,00,000 grows to ₹7,20,000
• Debt: ₹4,00,000 grows to ₹4,28,000
• Total: ₹11,48,000
• Equity weight now: about 62.7%

Your target was 60%. You are now 2.7 percentage points over. That is a small drift. After three or four strong years, it would be a large one. We will use this same example below to compare the two methods.

What is calendar-based rebalancing?

Calendar-based rebalancing means you rebalance at fixed intervals, whatever the market has done. The usual choices are monthly, quarterly, half-yearly or annually. Many Indian investors pick 1 April, the start of the financial year, because it fits neatly with tax planning. Others pick a birthday or Diwali.

Advantages of calendar rebalancing

• It is simple. You need one date in your diary and nothing else.
• It removes emotion. The date decides, not the news headlines or your mood.
• It limits trading. An annual schedule means at most one round of selling per year.
• It suits SIP investors. If your money already flows in monthly, a yearly check is easy to fit around it.

Disadvantages of calendar rebalancing

• It can be blind to large moves. If equity falls 30% in June and your date is in March, you wait nine months with a portfolio far from its target.
• It can trade for no reason. If the portfolio has barely drifted by your date, you may sell units, pay tax and incur costs for almost no benefit.
• The date is arbitrary. Nothing special about your chosen day makes it the right time to act.

What is threshold-based rebalancing?

Threshold-based rebalancing, also called band rebalancing or tolerance-band rebalancing, means you rebalance only when an asset class moves outside a range around its target. You can check the portfolio as often as you like, but you trade only when a limit is crossed.

Two rules of thumb are common.

The 5% rule. Rebalance when any asset class is more than 5 percentage points away from its target. With a 60% equity target, you act if equity goes above 65% or below 55%.

The 5/25 rule. Rebalance when an asset class is off target by 5 percentage points in absolute terms, or by 25% in relative terms, whichever comes first. This is better for smaller holdings. A 10% gold allocation hardly ever moves 5 points, but it can easily move 25% of its own size, going from 10% to 12.5% or down to 7.5%.

Advantages of threshold rebalancing

• It responds to real risk. Big market moves trigger action, quiet years trigger nothing.
• It avoids needless trades. If drift stays inside the band, you do not sell anything.
• It usually means lower tax. Fewer sales means fewer taxable events.

Disadvantages of threshold rebalancing

• It needs monitoring. You must look at your allocation often enough to notice a breach, at least monthly or quarterly.
• Bands need judgment. Too tight and you trade constantly. Too loose and you carry unwanted risk for long periods.
• Trades can come at awkward times. A breach during a sharp crash means buying equity when it feels worst, which is exactly the point, but not easy to do emotionally.

Calendar vs threshold rebalancing: worked example

Let us run the same portfolio through both methods in two different years.

Scenario 1: A good year for equity. This is the example from earlier, where equity rises 20% and debt rises 7%, leaving you at 62.7% equity.

• Calendar method (annual): On your date, you reset to 60:40. Target equity is ₹6,88,800, so you sell ₹31,200 of equity and move it to debt. The gain on that sale is small and falls well within the ₹1.25 lakh annual exemption on equity LTCG, so the tax cost is zero.
• Threshold method (5% band): Equity is at 62.7%, inside the 55% to 65% band. You do nothing. No sale, no cost.

Both outcomes are fine here. The threshold investor saved a trade. The calendar investor took a small step toward discipline.

Scenario 2: A bad year for equity. You start again with ₹6 lakh in equity and ₹4 lakh in debt. Equity falls 30% and debt rises 7%.

• Equity: ₹6,00,000 falls to ₹4,20,000
• Debt: ₹4,00,000 grows to ₹4,28,000
• Total: ₹8,48,000
• Equity weight: about 49.5%
• Threshold method: Equity has dropped below 55%, so the band is breached and you rebalance. Target equity is ₹5,08,800, so you buy about ₹88,800 of equity, funded by selling debt or using fresh cash. You bought equity cheaply and kept your risk where you wanted it.
• Calendar method: If this fall happened early in the year, you waited. If equity then fell further, you waited through the worst of it. If it recovered before your date, you missed the cheap buying chance altogether.

This is the core difference. Calendar rebalancing is predictable but slow. Threshold rebalancing is quicker to respond but needs attention.

Calendar vs threshold rebalancing: side-by-side comparison

Feature	Calendar-Based	Threshold-Based
Trigger	A fixed date	Drift beyond a set band
Effort	Low	Medium
Responds to market crashes	Slowly	Quickly
Number of trades	Fixed, even if not needed	Only when needed
Tax impact	Can be avoidable	Usually lower
Best for	Busy professionals, SIP investors	Investors who check regularly
Biggest risk	Missing large drifts between dates	Setting bands too tight or too loose

How does tax affect rebalancing in India?

Tax is the part most rebalancing guides skip, and in India it can change the answer. Every time you sell mutual fund units, you may trigger a capital gains tax event. Here are the current rules, which have stayed the same through Budget 2026.

• Equity funds (65% or more in equities), held up to 12 months: short-term capital gains tax at 20%.
• Equity funds, held more than 12 months: long-term capital gains tax at 12.5% on gains above ₹1.25 lakh in a financial year.
• Debt funds bought on or after 1 April 2023: gains are taxed at your income tax slab rate, whatever the holding period.
• Exit load: many funds charge around 1% if you redeem within a year, so check the scheme details first.

To see how much this matters, consider an investor with ₹5 lakh of long-term equity gains. The taxable amount is ₹3.75 lakh (₹5 lakh minus ₹1.25 lakh), and the tax is about ₹46,875, before cess. That is real money, and it directly cuts into the benefit of rebalancing.

This is a strong argument for the threshold method. Fewer, larger, better-timed trades usually mean a smaller tax bill than a fixed schedule that sells something every year.

Please check the latest rules or speak to a tax professional before acting, since tax laws can change.

What is the most tax-efficient way to rebalance?

You can often rebalance without selling anything at all. Three methods work well for Indian investors.

1. Rebalance with fresh money. Send your new SIP amounts or lump sums to the underweight asset class. If equity is too high, put new money into debt or gold until the balance returns. This avoids capital gains entirely and costs nothing.

2. Use the annual ₹1.25 lakh exemption. If you need to sell equity, try to keep your long-term gains within ₹1.25 lakh for the year. Those gains are tax-free. You can sell part of the holding, move the money to debt, and pay no tax on that portion.

3. Reset your cost price on purpose. Because India has no wash-sale rule for mutual funds, some investors sell units with long-term gains up to the exemption limit and buy them back, which raises their purchase price and lowers future tax. Keep exit loads and any switching costs in mind before doing this.

You can also sell units that are at a loss to offset gains elsewhere in the same financial year. Do this only when it fits your plan, and never for tax reasons alone.

What is hybrid rebalancing, and why do many investors prefer it?

Hybrid rebalancing combines both approaches. You review your portfolio on a calendar schedule, but you trade only if the drift has crossed your threshold.

For example, you might check your allocation every quarter, and act only if any asset class is more than 5 percentage points off target. If nothing has crossed the line, you leave the portfolio alone and wait for the next check.

This gives you the best of both. You get the simplicity of a schedule, so you never forget to look. You also get the efficiency of a band, so you do not trade for no reason. For taxable portfolios in India, where each sale has a cost, this is often the most practical method.

How often should you rebalance your portfolio?

There is no single correct answer, but research and common practice point in the same direction. Well-known studies, including work published by Vanguard, found little meaningful difference in long-term results between monthly, quarterly and annual rebalancing, while less frequent rebalancing meant lower costs. Many investors settle on a review once or twice a year with a 5% band for trades.

A good starting point for most Indian retail investors:

• Review frequency: every six months, or once a year if you invest mainly through SIPs
• Trade trigger: 5 percentage points of drift for major asset classes
• Smaller holdings such as gold: use the 5/25 rule, or a band of 2 to 3 percentage points
• Method of correction: new money first, selling only if new money is not enough

A very tight band, such as 1 or 2 percentage points on a large holding, usually creates more trades than benefit once costs and tax are counted.

Which strategy is right for you?

Choose based on how you actually live, not on what looks best on paper.

Choose calendar rebalancing if you invest mostly through SIPs, you prefer a simple routine, and you are unlikely to check your portfolio between dates. Pick one date and keep to it.

Choose threshold rebalancing if you are comfortable looking at your allocation every month or quarter, you hold a larger portfolio, or you want to keep taxable sales to a minimum.

Choose the hybrid method if you want a clear routine and efficient trading. For most people reading this, this is the one to start with.

Also consider using an asset allocation fund or balanced advantage fund for part of your money. These funds rebalance automatically inside the scheme, and the tax treatment depends on the fund’s equity exposure. They cost slightly more in fees but save you the effort.

Common portfolio rebalancing mistakes to avoid

• Rebalancing too often. Monthly rebalancing usually adds cost without adding protection.
• Ignoring tax and exit load. Always check the cost of a sale before you make it.
• Having no written target. You cannot rebalance without a target allocation. Write yours down.
• Rebalancing based on market predictions. The point is to follow a rule, not to guess what happens next.
• Forgetting your goals have changed. If you are closer to retirement or a big expense, your target itself may need to change. That is a different decision from rebalancing.
• Skipping rebalancing in a rally. It feels wrong to sell winners, but a drifted portfolio holds more risk than you planned for.

A simple step-by-step rebalancing plan

1. Write down your target allocation. For example, 60% equity, 30% debt, 10% gold.
2. Choose your method. Calendar, threshold or hybrid.
3. Set your band. Five percentage points is a sound starting point.
4. Pick your review dates. Six-monthly or annual, and put them in your calendar.
5. At each review, calculate your actual allocation. A simple spreadsheet works fine.
6. If a band is breached, correct it with new money first.
7. If you must sell, check the gain, the holding period and the exit load.
8. Record what you did and why. This keeps you honest and helps you improve.

Frequently asked questions about portfolio rebalancing

What is the difference between calendar and threshold rebalancing?

Calendar rebalancing resets your portfolio at fixed dates, such as once a year. Threshold rebalancing resets it only when an asset class drifts beyond a set limit from its target, such as 5 percentage points. Calendar is simpler, while threshold is more responsive and often cheaper in tax.

How often should I rebalance my mutual fund portfolio in India?

Most investors do well with a review every six to twelve months, and trades only when an asset class is more than about 5 percentage points away from target. Rebalancing more often than quarterly usually adds cost without a clear benefit.

What is the 5% rule for portfolio rebalancing?

The 5% rule says you should rebalance when any asset class moves more than 5 percentage points away from its target weight. If your equity target is 60%, you act when it goes above 65% or below 55%.

What is the 5/25 rule?

The 5/25 rule says to rebalance when an asset class is off target by 5 percentage points in absolute terms or by 25% in relative terms, whichever happens first. It works better than a flat 5% for small holdings like gold.

Is rebalancing a mutual fund portfolio taxable in India?

Yes, if you sell units. Equity fund gains are taxed at 20% if short-term and 12.5% if long-term, with the first ₹1.25 lakh of long-term gains each financial year exempt. Debt fund gains on units bought on or after 1 April 2023 are taxed at your slab rate. You can avoid tax by rebalancing with fresh money instead of selling.

Can I rebalance my portfolio using SIPs?

Yes. Redirect your new SIP contributions toward the underweight asset class until your allocation returns to target. This method has no capital gains tax and no exit load, which makes it the cheapest way to rebalance.

Is calendar or threshold rebalancing better?

Neither wins in every case. Calendar is better for simplicity and discipline. Threshold is better for responding to large market moves and limiting taxable sales. A hybrid method, which reviews on a schedule and trades on thresholds, suits most retail investors.

Do I need to rebalance if I only invest in one index fund?

If you hold only one fund, there is nothing to rebalance. But if that fund is your whole equity allocation and you also hold debt or gold, those parts can still drift against each other, and the same rules apply.

Final thoughts

Rebalancing is not about beating the market. It is about keeping the risk you chose, year after year, without letting a hot market quietly change your plan.

The best strategy is the one you will actually follow. A calendar date you keep is better than a perfect threshold system you forget. For most Indian investors, a half-yearly review with a 5% band, and fresh SIP money used first, gives sound discipline at a low cost in tax and effort.

This article is for educational purposes and is not personalised investment or tax advice. Please consult a SEBI-registered investment adviser or a qualified tax professional before making decisions about your portfolio.