Portfolio rebalancing is one of the most misunderstood practices in retail investing. Done correctly, it controls risk and enforces discipline. Done naively, it generates unnecessary tax drag and transaction costs that erode returns.
The Indian Tax Context
As of FY2025-26, the relevant tax rates for equity rebalancing are: Short-Term Capital Gains (STCG, holding period ≤12 months) taxed at 20%; Long-Term Capital Gains (LTCG, >12 months) taxed at 12.5% above ₹1.25 lakh exemption per year. The 12-month cliff creates a powerful incentive to hold positions beyond a year before trimming overweight allocations.
Drift Tolerance Bands
Rather than calendar-based rebalancing (which ignores tax efficiency), threshold-based rebalancing triggers action only when a holding drifts beyond a tolerance band from its target allocation. Research on Indian large-cap portfolios suggests 5% absolute deviation as the sweet spot:
- Narrower bands (2-3%) → 4–6 rebalancing events per year, frequent STCG triggers
- 5% bands → 1–2 events per year, most positions age past the 12-month LTCG threshold
- Wider bands (8-10%) → Insufficient risk control; sector concentration risk accumulates silently
Tax-Aware Rebalancing in Practice
The most tax-efficient approach combines drift-triggered rebalancing with LTCG timing. When a position crosses the 5% drift threshold:
- Check the purchase date — if within 11 months, set a calendar reminder to trim at month 12+
- Use fresh SIP inflows or dividend reinvestment to rebalance underweight positions without selling
- Apply LTCG exemption (₹1.25 lakh) by selectively harvesting the cheapest lots first
Spectrum's Rebalancing Tools module shows the current drift from your target allocation for every holding, displays holding periods, and estimates the tax impact of each potential trade — letting you make informed rebalancing decisions rather than mechanical calendar-based ones.