Debt Mutual Funds Explained: Types, Risk and Taxes
A debt mutual fund lends your money out. It buys government bonds, corporate bonds, treasury bills, commercial paper and certificates of deposit, and your return comes from the interest those instruments pay plus any change in their market value.
A debt fund is a pooled scheme holding fixed income securities rather than shares, so its returns are driven by interest rates and by the creditworthiness of the borrowers it lends to. Nothing here is promised. The NAV moves daily, and in a bad week it moves down.
This piece covers the two engines behind the return, the SEBI categories ranked by risk, a worked example on Rs 5,00,000, the tax rules that changed in 2023, and the mistakes that cost beginners most.
Where does a debt fund’s return actually come from?
Two sources, and they behave nothing alike. The first is accrual. Every bond pays a coupon. Add those up, subtract the expense ratio, and you get the steady drip that makes debt returns look smooth. A portfolio yielding 7.2% with a 0.30% expense ratio accrues roughly 6.9% a year if nothing else happens.
The second is mark to market. Bond prices move inversely to interest rates, so when market yields fall, existing higher coupon bonds gain value and NAV jumps. When yields rise, NAV falls. This is where the surprises live.
Short maturity funds are almost all accrual, long maturity funds mostly mark to market. That is why a liquid fund barely wobbles while a gilt fund can drop 3% in a month.
The two risks you are actually taking
Interest rate risk
Measured by modified duration, printed in every monthly factsheet. Rough rule: duration of 4 years means a 1% rise in yields knocks about 4% off portfolio value, and a 1% fall adds about 4%. Longer duration means bigger swings both ways. That is a design choice, not a defect.
Credit risk
The chance a borrower pays late or not at all. Ratings run from AAA down through AA, A and BBB. A fund holding AA and A paper earns a higher yield precisely because that paper can default.
Credit risk does not build gradually. It arrives as a single downgrade that writes down a holding overnight. So read the scheme’s riskometer label before buying anything at the higher end of the scale.
The categories, lowest risk to highest
SEBI defines sixteen debt categories so two funds with the same label hold broadly similar things. Confirm any specific scheme’s current portfolio in its factsheet.
| Category | Maturity or duration mandate | Rate sensitivity | Typical use |
|---|---|---|---|
| Overnight | Securities maturing in 1 day | Almost nil | Cash parked for days |
| Liquid | Up to 91 days maturity | Very low | 1 to 3 months |
| Ultra short duration | Macaulay duration 3 to 6 months | Low | 3 to 6 month goals |
| Short duration | Macaulay duration 1 to 3 years | Moderate | 1 to 3 years |
| Corporate bond | Min 80% in highest rated corporate paper | Moderate | Core debt allocation |
| Credit risk | Min 65% in AA and below | High credit risk | Small satellite holding |
| Gilt | Min 80% in government securities | High | No credit risk, full rate risk |
| Long duration | Macaulay duration above 7 years | Highest | Falling rate cycles only |
Money market, low duration, banking and PSU, dynamic bond and floater funds fill the gaps. The pattern holds throughout: higher yield, larger drawdown. For how these fit beside equity and hybrid schemes, see our breakdown of the main types of mutual funds.
Worked example: what a 1% rate move costs you
You invest Rs 5,00,000 in a fund with a portfolio yield of 7.2%, modified duration of 4 years and an expense ratio of 0.35%.
Accrual for the year is 7.2% minus 0.35%, so 6.85%. On Rs 5,00,000 that is Rs 34,250.
Now suppose market yields rise 1%. The mark to market hit is duration multiplied by the yield change, so 4 multiplied by 1%, giving 4%. On Rs 5,00,000 that is Rs 20,000.
Net result: Rs 34,250 minus Rs 20,000, so Rs 14,250, about 2.85% for the year. Positive, but far below what the yield figure suggested.
Flip the move. If yields fall 1%, you gain Rs 20,000 on top of Rs 34,250, so Rs 54,250, about 10.85%. Same fund, same year, an 8 percentage point swing decided by rates alone.
Run the same 1% rise through a liquid fund with duration near 0.1 years and the hit is 0.1%, or Rs 500. Barely visible. That is why short duration categories hold money you may need next month.
How are debt mutual funds taxed in India?
This changed in a way that matters. Debt mutual fund units bought on or after 1 April 2023 are specified mutual funds under Section 50AA. Gains are added to your income and taxed at your slab rate however long you hold, with no indexation.
So a 30% bracket taxpayer earning 7% gross keeps about 4.9%. A fixed deposit is taxed at slab rate too, but FD interest is taxed as it accrues each year while debt fund gains are taxed only on redemption. Your money compounds untaxed until you exit.
Two practical points. Nobody deducts this tax for you. And units bought before 1 April 2023 follow the older rules, so check purchase dates in your statement. Our guide to how mutual fund returns are taxed covers the computation.
Mistakes beginners make with debt funds
- Buying the fund with the best one year return. Last year’s chart topper usually took the most duration or credit risk, and that risk is still in the portfolio.
- Treating yield to maturity as a promised return. It is a snapshot of the current portfolio, not a forecast.
- Using a gilt or long duration fund for a six month goal.
- Ignoring the expense ratio. On a fund yielding 7%, a 1.2% expense ratio takes a sixth of your gross return before tax.
- Assuming debt means safe. Credit events have caused real capital loss in Indian debt funds.
A plain risk note: debt funds are market linked. No capital protection, no assured return, and the riskometer is the minimum you should read before investing.
Frequently Asked Questions
Can a debt mutual fund give negative returns?
Yes, over short periods. A sharp rise in yields pushes bond prices down, so a fund with meaningful duration can post a negative month or even a negative quarter. A downgrade in a large holding can also drop the NAV suddenly. Over holding periods that match the fund’s duration, negative outcomes get much less likely, but they are never ruled out.
How long should I stay invested in a debt fund?
Match your holding period to the fund’s duration. Roughly: overnight and liquid funds for days to three months, ultra short and low duration up to a year, short duration and corporate bond funds for one to three years, and gilt or long duration only if you can hold several years and tolerate losses along the way.
Is a debt fund better than a fixed deposit for tax?
Neither wins on the rate, since both are taxed at your slab. The difference is timing. FD interest is taxed every year as it accrues, while debt fund gains are taxed only when you redeem, so your money compounds on the full amount until then. Over five years at a 30% slab, that deferral is worth having.
What is the difference between YTM and the return I will get?
Yield to maturity is what the current portfolio would earn if every bond were held to maturity, nothing defaulted and the manager bought nothing new. In practice the manager trades, yields move and expenses come off. Treat YTM as an indication of accrual, adjust for the expense ratio, then expect mark to market to add or subtract.
How do I check the credit quality of a debt fund I already own?
Open the scheme’s monthly portfolio disclosure or factsheet on the AMC website. It lists every holding with its rating, plus a summary showing the share sitting in AAA, AA, A and sovereign paper. Note modified duration and average maturity in the same document. Both shift month to month as the manager repositions the book.
Key Takeaways
- Debt returns come from accrual plus mark to market. Short maturity funds are mostly accrual, long maturity funds mostly mark to market.
- Modified duration multiplied by the yield change estimates the NAV impact. Duration 4 and a 1% rise means roughly a 4% hit.
- Credit risk arrives all at once. A fund yielding noticeably more than its peers is being paid for a risk you should be able to name.
- Units bought on or after 1 April 2023 are taxed at your slab rate with no indexation, whatever the holding period, under Section 50AA.
- Tax deferral until redemption is the main structural edge debt funds keep over fixed deposits at the same slab.
- Match the fund’s duration to your goal’s timeline. That single rule prevents most disappointment with debt funds.
