Ramachandran has been getting amazing returns in his equity investments from a massive, multi-year bull run. But after a sudden geopolitical development that led crude oil prices to soar again this year, he fears an upcoming market crash will wipe out all his profits.
But he does not want to shift his money into a savings account with only 2.50% yearly interest, which is currently being offered at most major Indian banks. He has heard Long-term Debt Funds can deliver strong double-digit returns during economic slowdowns, but wonders how reliable that really is.
Like many other investors, Ramachandran now wants to know, “<i>How can my money grow under such a long-term fund scheme and get good returns in 10 years?</i>”
How Market Interest Rate Controls the NAV?
Suppose an investor invests ₹10,000 in a Long-Term Debt Mutual Fund. The fund manager uses that money to buy a basket of 10-year government bonds at an 8% coupon rate (yearly interest rate), which follows the current interest rate of 8%. The investor’s fund was issued with a starting NAV of ₹100 per unit.
Suppose, later on, RBI raises its Repo Rate to 10%. Instantly, a new batch of government bonds is benchmarked against it and issued at a 10% coupon rate.
On the open market, the existing old fund units are newly valued at the market price of ₹88 per unit. The old bonds with the lower interest rate are now less attractive compared to the newly launched bonds. To match the lower demand, the market value of the old bonds is lowered to ₹88 per unit. A point to note here: Neither the investor nor the fund manager has sold anything yet.
The Daily Market Valuation Formula for Bonds:
Using the principal amount of ₹100 as the future value of the bond in 10 years, the present value can be arrived at by dividing by the Discount Factor. This factor can be thought of as being the opposite of a compounding factor that is multiplied to find the compounded growth.
The Annuity Factor represents the series of equal interest payments received yearly.
Market Value of Bond
= Present Market Value of Coupon Payments + Present Market Value of Principal
= Yearly Coupon / Interest Payments × Annuity Factor + Principal × Discount Factor
Discount Factor
= 1 / {(1 + Present Market Interest Rate) ^ Years to Maturity}
Annuity Factor
= (1 - Discount Factor) / Present Market Interest Rate
Change in Market Valuation and NAV of Bond with change in Market Interest Rate:
For illustration, assume the fund's ₹100 NAV corresponds directly to a single ₹100 face-value bond paying an 8% annual coupon. In practice, this coupon is paid to the fund and is reflected in the fund's NAV under the Growth option, or distributed as income under the IDCW option. Hence, the bond pays ₹8 per unit as interest payouts every year.
With the present market interest rate that continues at 8%, and matching the 8% bond coupon rate,
Discount Factor
= 1 / (1 + 0.08) ^ 10 = 0.4631
Annuity Factor
= (1 - 0.4631) / 0.08 = 6.7112
Market Value of Bond with 8% Market Interest rate
= ₹8 per unit × 6.7112 + ₹100 per unit × 0.4631 = ₹53.69 + ₹46.31 = ₹100.0 per unit = old NAV
But when the present market interest rate rises to 10%, and the bond coupon rate is locked at 8%,
Discount Factor
= 1 / (1 + 0.1) ^ 10 = 0.3855
Annuity Factor
= (1 - 0.3855) / 0.1 = 6.145
Market Value of Bond with 10% Market Interest rate
= ₹8 per unit × 6.145 + ₹100 per unit × 0.3855 = ₹49.16 + ₹38.55 = ₹87.71 per unit = new NAV
If the present market interest rate falls to 6% instead of rising, and the bond coupon rate is locked at 8%,
Discount Factor
= 1 / (1 + 0.06) ^ 10 = 0.5584
Annuity Factor
= (1 - 0.5584) / 0.06 = 7.36
Market Value of Bond with 6% Market Interest rate
= ₹8 per unit × 7.36 + ₹100 per unit × 0.5584 = ₹58.88 + ₹55.84 = ₹114.72 per unit = new NAV
This clearly establishes an inverse relationship between the market interest rate and NAV. Fund management expenses have been neglected here.
How Wealth Building Works in Long-Term Debt Funds?
The investor is holding his 10-year long-term debt fund, which he had bought at an 8% coupon rate and an NAV of ₹100.
Now, RBI usually acts in three ways regarding the Repo Rate, and accordingly, after the investor makes their investments, the market interest rate can either remain at 8%, spike to 10%, or fall to 6%.
Wealth Generation Strategy after Interest Rate Cuts:
Often, under improving economic conditions, RBI will cut interest rates to boost the economy further. The long-term debt funds issued before this, and offering higher interest rates for their bonds, automatically increase in value. Fund managers will now sit on this growing profit and sell their bonds just when the interest rates may start going up again.
Wealth Generation Strategy after Interest Rate Hikes:
When RBI raises interest rates, the long-term debt funds bought before this hike now lose value in the market<i>.</i>
This immediate loss can be overcome using the Reinvestment Mechanism. Fund managers use the interest payouts from the old bonds to buy new bonds with higher and more attractive rates. Over time, the massive compounding interest from the new bonds completely overwhelms the temporary paper drop. Long-term funds realise this recovery for an extended period, thereby building considerable wealth. This is available in the growth option only.
The Complete Wealth Generation Cycle:
By using the correct strategy at the relevant stage of the interest rate cycle, fund managers can build a generous amount of wealth for their investor portfolios, through many cycles.
Reading the Interest Rate Cycle
Interest rates are mainly driven by two macroeconomic factors: Inflation and Economic Growth (GDP). RBI considers both when deciding the Repo Rate. While inflation is the RBI’s primary mandate, economic growth determines whether the RBI has room to stimulate the economy through lower interest rates or needs to tighten monetary policy to control rising prices.
Broadly speaking, when economic growth is falling, then interest rates are cut to boost the economy, and when inflation increases, then interest rates are hiked to cool inflation down. Economic growth often goes hand in hand with inflation.
While there is no fixed formula for predicting the RBI’s next repo rate decision, investors can monitor the following factors and observe the overall economic conditions to make informed decisions.
- The Monetary Policy Committee (MPC) statement — It is published by RBI every two months and explicitly signals RBI’s stance. Rate cuts often follow the mention of a “neutral” stance.
- The Inflation trend (CPI-based) — Investors can follow inflation against RBI’s inflation targets on the MoSPI page on Inflation data. RBI is mandated to maintain the CPI inflation rate at 4% with a tolerance of 2%, according to Section 45ZA in The Reserve Bank of India Act, 1934. Observing sustained readings away from the target could signal upcoming rate cuts.
- The real GDP growth trend — It is reported on the MoSPI page on GDP data. A sustained slowdown in real GDP growth, particularly when inflation is under control, may increase the likelihood of RBI reducing repo rates to support economic activity. Conversely, strong economic growth may reduce the need for lower interest rates.
- The RBI Repo rate trend — It is reported on the RBI website, under the Policy rates section. A pause after a rate-hiking cycle can be indicative of a peak in interest rates, but not conclusive. RBI has been known to hold rates steady over extended periods.
No single signal may be reliable. Investors track all of these and get better at predicting rate movements with time and practice. Still, no investor can make perfect predictions, which is why staggered investing is used to save energy from having to identify precise investment entry points.
Sticky Inflation and Stagflation: In both these cases, economic growth is weak, but inflation remains high. RBI has to maintain high interest rates to fight inflation, despite weak economic growth. This is a major hurdle in a long-term fund wealth creation strategy, as the interest rate cycle timeframe now becomes much longer. As a result, profits made from changing bond prices and NAV take much longer.
Staggered Investing: A Better Entry Strategy for Long-Term Debt Funds
As an investor, the usual strategies of monthly SIPs and lump-sum investments may not be the best in relation to long-term debt funds.
With SIPs spread out evenly across a calendar and without having any regard for the changing rates, it is an excellent investment strategy in most cases. But it is not designed for catching bonds before a rate cut.
A lump sum concentrates the entire investment into a single date, which works well if timed right, but leaves the full investment exposed if rates move against the investment right after.
Staggered Investing is a strategy where the total investment is divided over a window of 3 to 6 months.
This strategy sits between the other two: like a lump sum, the investor still chooses a window when conditions feel favorable, but like a SIP, the investor is not betting everything on a single day either. While this cannot promise the perfect entry point, it reduces the risk of getting the timing badly wrong.
For example, if you invest an entire lump sum in one go and the rates move against you right after, the whole investment feels that hit. But if the investment is split across 3-4 entry points over several months, one is averaging across different rate conditions. So if one block enters at a bad time, the others may enter at better ones, and the overall damage to the portfolio is smoothed out rather than concentrated.
Minimizing Default Risk with Macaulay Duration Mandates
SEBI’s Master Circular for Mutual Funds, 2026 (Chapter 3, Para 3.8.2, No. 9, Long Term Fund) strictly outlines that a registered Long-Term Debt Fund must maintain a portfolio Macaulay duration greater than 7 years.
This safety net works because Indian corporations rarely issue liquid bonds with maturities stretching out 15 to 30 years. The only entity consistently borrowing capital on those timelines is the Government of India. The long-term fund managers are practically forced to park their money in sovereign Government Securities (G-Secs).
Tax Impact on Long-Term Debt Mutual Funds
For building a 10-year playbook like Ramachandran, investors need to know that the tax rules for debt mutual fund units bought on or after 1st April 2023 have changed permanently (Income Tax Act 1961, Section 50AA). The old perks related to indexation and Long-Term Capital Gains (LTCG) tax rates are no longer applicable.
New tax laws on mutual fund gains: Every profit made from a debt fund is added directly to the investor’s gross total income and taxed at their personal Income Tax Slab Rate, no matter the term of the fund. The income slabs are detailed in Section 25, Finance Act 2025, as an amendment of Section 115BAC of the Income Tax Act.
Recall the scenario from earlier: NAV rising from ₹100 to ₹114.8 per unit, a profit of ₹14.8 per unit. With a total investment of ₹10,000, the investor buys exactly 100 units. So the total profit at the new NAV (₹114.72) is: 100 units × ₹14.72 = ~ ₹1,480 total profit
Since this gain is now taxed at your income slab rate, what you actually keep depends on your bracket:
The Tax Rebate Rule: For debt fund gains, which are now considered income, the tax rebate laws apply (Section 87A, Income Tax Act, 1961). For annual incomes under ₹12 Lakhs, a rebate of ₹60,000 is applicable.
Tax on Gains is Deferred Until Sold: With a mutual fund, the investor pays the total tax when redeeming their units. The money compounds completely tax-free inside the fund for the entire 10 years.
Why SIPfund?
Your SIPfund app provides you with algorithm-based goal tracking and a consolidated view of all your investments. It tracks your holdings against your goals over time and flags progress, so you're not left guessing whether a rate move has changed your outlook. Your investments are also safe, as they go through NSE's secure mutual fund platform and directly to the fund house.
We are an AMFI-registered mutual fund distributor, and our experts provide personalized consultation on goal planning, fund selection, and guidance during market volatility.
The Final Verdict
A savings account offers safety and liquidity, but its return may not keep pace with inflation. Long-term debt funds can deliver meaningful returns when RBI cuts interest rates in a slowdown, specifically in a growth option, but stagflation is an exception here. As an investor, it is good to remember that these funds are not risk-free, and outcomes vary.
Run the numbers before you decide. Call our team today on 95133 55661 to get step-by-step guidance.
Interested in investing in long-term debt funds yourself? Start here on our app (iOS or Android).
<i>Disclaimer: The information provided in this article is for educational purposes only and does not constitute investment advice or a recommendation to buy or sell any mutual fund. Mutual Fund investments are subject to market risks, read all scheme-related documents carefully.</i>
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