Clean vs Dirty Price and Accrued Interest in Indian Bonds

Q: What is the exact formula for clean price and dirty price?

The core relationship is: Dirty Price = Clean Price + Accrued Interest. The clean price is the pure market value of the bond excluding interest. The dirty price (or invoice price) is the total amount paid by the buyer and received by the seller upon settlement.

Clean vs Dirty Price and Accrued Interest in Indian Bonds

Imagine browsing an online bond platform or your exchange broker's terminal looking at listed corporate debentures. You spot an attractive instrument listed at a price of Rs. 1,005 per unit against a face value of Rs. 1,000. You enter an order for 10 units, expecting an outflow of Rs. 10,050. When you advance to the final order confirmation screen, however, the invoice demands Rs. 10,480.

That additional Rs. 430 is not a hidden broker markup, an exchange charge, or a software platform fee. It represents accrued interest, and the transition between those two numbers is the difference between a bond's clean price and its dirty price. In the Indian fixed income market, bonds are quoted using clean prices, but every secondary market trade settles using dirty prices.

Understanding this distinction prevents settlement-day surprises, clarifies tax liabilities, and ensures precise yield evaluation. This guide walks through the mechanics of coupon accrual, Indian day-count conventions, the buyer-seller settlement mechanism, and the accounting nuances governing trades on stock exchanges and regulated bond portals.

Key Takeaways

Clean price reflects pure market value — it is the quoted price of the bond on exchange screens, excluding any interest built up since the last payment date.
Dirty price is the actual settlement amount — also known as the invoice price, it equals the clean price plus accrued interest. Buyers pay the dirty price; sellers receive the dirty price.
Accrued interest compensates the seller — because bond issuers pay coupons periodically (annually, semi-annually, or quarterly) to whoever holds the bond on the record date, the buyer must pay the seller for the days the seller held the bond during the ongoing coupon cycle.
Day-count conventions determine exact accrual — corporate Non-Convertible Debentures (NCDs) in India typically use Actual/Actual or Actual/365 conventions, whereas money market instruments and commercial paper may use Actual/365 or 30/360.
The clean price chart is smooth; the dirty price chart is a sawtooth — clean prices change only when market yields, credit ratings, or base interest rates shift. Dirty prices rise steadily every single day as interest builds, dropping abruptly on the ex-coupon date.
TDS on the coupon falls on the holder of record — the issuer deducts Tax Deducted at Source (TDS) on the gross coupon paid on the payment date, meaning buyers must track accrued interest paid to correctly reconcile their taxable interest income.
Settlement date governs the calculation — interest accrues right up to the day before the settlement date (T+1 on Indian exchanges), not the trade execution date.

Why Bonds Trade on Clean Price but Settle on Dirty Price

When you purchase an equity share in the secondary market, the price you see on the screen is the exact price you pay per share (plus brokerage and statutory levies). Fixed-income securities operate under a dual-pricing mechanism because of how coupon distributions work.

A bond is a loan that pays interest on designated scheduled dates. For example, a 9% annual coupon bond with a face value of Rs. 1,000 pays Rs. 90 on April 1 every year. If an investor holds this bond from April 1 to September 30 (183 days) and sells it to you on October 1, the seller has earned six months of interest.

However, the issuing corporation will not split its annual payout. When April 1 of the following year arrives, the issuer looks at the depository register (NSDL or CDSL) on the record date and pays the entire Rs. 90 annual coupon to whoever holds the bond on that date: you. +-------------------------------------------------------------------------+ | THE COUPON CYCLE TIMELINE | +-------------------------------------------------------------------------+ Last Coupon Date Trade Settlement Next Coupon Date (April 1) (October 1) (March 31 / April 1) |----------------------------------|-------------------------| <-------- Seller Earned ----------><----- Buyer Will Earn ---> (183 Days Accrual) (182 Days Accrual)

 Seller held bond for 183 days.     Buyer receives FULL 365-day coupon
 Buyer pays seller for these days   from issuer on payment date.
 via Accrued Interest upfront.

+-------------------------------------------------------------------------+

Because you will receive the full 365 days of interest despite holding the bond for only 182 days, the market rules require you to reimburse the seller upfront for the 183 days they owned the bond.

Why Exchanges Quote the Clean Price

If trading terminals displayed dirty prices, bond prices would artificially rise every calendar day simply because the coupon date is approaching, even if the underlying company's creditworthiness or broader interest rates did not budge. The day after the coupon is paid, the dirty price would plummet by the full coupon value overnight.

Such fluctuations make it nearly impossible for an investor to gauge whether a bond has become fundamentally cheaper or more expensive due to supply, demand, or macroeconomic conditions. By stripping out daily interest accrual, the clean price isolates real market dynamics — such as shifts in the benchmark yield curve or adjustments in credit risk premiums.

When you evaluate offerings on OBPP platforms or the secondary market, the listed quote is generally the clean price, while your checkout summary adds the accrued interest to display the final dirty price.

How Accrued Interest Is Calculated in India

The mathematical foundation of accrued interest is straightforward: Accrued Interest = Face Value × (Coupon Rate ÷ 100) × (Accrual Days ÷ Days in Coupon Period)

And the resulting settlement amount: Dirty Price = Clean Price + Accrued Interest

To calculate the exact figure, three inputs are required:

The annual coupon rate and payment frequency (annual, semi-annual, quarterly, monthly).
The number of days elapsed from the previous coupon payment date up to (but not including) the settlement date.
The recognized day-count convention for that specific asset class.

Day-Count Conventions in the Indian Market

Different segments of the Indian fixed income landscape adhere to specific standards set by the Reserve Bank of India (RBI), the Fixed Income Money Market and Derivatives Association of India (FIMMDA), and the Securities and Exchange Board of India (SEBI):

Debt Instrument Type	Standard Day-Count Convention	Description
Central Government Securities (G-Secs)	Actual/Actual	Counts real calendar days between coupons; divides by actual days in the year (365 or 366).
State Development Loans (SDLs)	Actual/Actual	Mirrors central sovereign paper across all state government borrowings.
Corporate Bonds & NCDs	Actual/Actual (or Actual/365)	Most modern private and public NCDs adopt Actual/Actual as specified in the issue prospectus.
Commercial Paper (CP) & Certificates of Deposit (CD)	Actual/365	Money market debt calculates interest on exact elapsed days divided by 365.
Treasury Bills (T-Bills)	Actual/365	Traded on a discount-to-face-value basis using 365 days.

Step-by-Step Calculation Example

Suppose an investor purchases an NCD issued by an infrastructure NBFC with the following parameters:

Face Value: Rs. 1,000
Coupon Rate: 9.50% per annum (payable annually)
Last Coupon Payment Date: June 30, 2026
Trade Execution Date: October 14, 2026
Settlement Timeline: T+1 (Settlement takes place October 15, 2026)
Clean Quoted Price: Rs. 1,012.00
Day-Count Convention: Actual/Actual (365 days in 2026–27)

Step 1: Determine the Elapsed Days

Count the actual calendar days from June 30, 2026 up to October 15, 2026 (the settlement date is excluded from the seller's accrual; interest belongs to the buyer on and after settlement):

July: 31 days
August: 31 days
September: 30 days
October: 14 days (up to October 14 inclusive)
Total Accrual Days = 31 + 31 + 30 + 14 = 106 days

Step 2: Compute Accrued Interest

Annual Coupon Amount = Rs. 1,000 × 9.50% = Rs. 95.00 Daily Interest = Rs. 95.00 ÷ 365 = Rs. 0.260274 Accrued Interest = 106 days × Rs. 0.260274 = Rs. 27.59

Step 3: Compute Dirty Price

Dirty Price = Rs. 1,012.00 (Clean Price) + Rs. 27.59 (Accrued Interest) = Rs. 1,039.59

If you purchase 100 debentures, your clean outlay is Rs. 1,01,200, the accrued interest paid to the seller is Rs. 2,759, and your total bank transfer on settlement day is Rs. 1,03,959.

Reviewing the bond settlement process in India helps clarify how funds and securities clear through the clearing corporation on T+1.

Clean Price vs Dirty Price: Key Structural Differences

To visualize how these two pricing methods interact across a bond's annual lifecycle, examine their structural differences:

Attribute	Clean Price	Dirty Price (Invoice Price)
What it Represents	The bond's market value based strictly on prevailing interest rates, credit rating changes, and issuer fundamentals.	The comprehensive cash amount required to settle the trade, encompassing capital value plus accumulated interest.
Quotation Standard	The default quote shown on exchange screens (NSE, BSE, NDS-OM) and primary platform listings.	The final checkout figure calculated after verifying the settlement date.
Price Pattern Over Time	Smooth line; adjusts only when market yields, credit spreads, or liquidity conditions change.	"Sawtooth" pattern; climbs steadily every day as interest builds, then drops sharply on the ex-coupon date.
Accrued Interest Inclusion	Excludes accrued interest entirely.	Includes all accrued interest up to the settlement date.
Yield Calculation Role	Used in tracking historic price performance and capital appreciation.	Mandatory input for calculating exact Yield to Maturity (YTM) and internal rate of return (IRR).
Settlement Usage	Not used for physical cash transfers.	The exact amount debited from buyer and credited to seller by the clearing house.
+-------------------------------------------------------------------------+
THE SAWTOOTH PATTERN OF DIRTY PRICING
+-------------------------------------------------------------------------+
Price
^
Dirty Price (Climbs daily due to accrued interest)
/	/	/
/	/	/
/	/	/
/	/	/
/	/	/
-----/-----+----/-----+----/-----+---- Clean Price (Stable)
/	/	/
/	/	/
/	/	/
0---+---------v-+--------v-+--------v----------------------------> Time

 Coupon   Ex-Div     Coupon     Coupon
 Paid     Drop       Paid       Paid

+-------------------------------------------------------------------------+

When comparing opportunities across the primary vs secondary bond market, note that primary public issuances do not involve accrued interest upon initial allotment — you purchase at par (face value). In contrast, virtually all secondary trades involve an accrued interest component unless the trade settles on the exact coupon date.

The Settlement Cash Flow: Who Pays What to Whom?

In the Indian debt market, trades matched on the National Stock Exchange (NSE) or Bombay Stock Exchange (BSE) clear through NSE Clearing Limited (NCL) or the Indian Clearing Corporation Limited (ICCL). When trading via registered Online Bond Platform Providers (OBPPs), orders are routed through the Request for Quote (RFQ) platform or the secondary exchange order books.

Understanding who handles the cash at each phase ensures transparency:

1. Trade Execution (Day T)

The buyer places a bid based on yield or clean price. Once the counterparty matches the order, the trading system locks in the clean price and automatically computes accrued interest based on the predetermined settlement date (T+1).

2. Settlement Processing (Day T+1)

The buyer's bank account or trading ledger is debited for the dirty price multiplied by the number of units.
The clearing corporation pays the seller the full dirty price.
Simultaneously, the seller's demat account at NSDL or CDSL is debited for the units, which are transferred directly into the buyer's demat account.
The seller walks away with their original principal investment (subject to capital gains/losses based on the clean price) PLUS the interest earned for the days they held the bond during the current cycle.

3. The Subsequent Coupon Date

Several months later, when the issuer prepares the coupon distribution, it consults the Benpos (Beneficiary Position) statement generated by the depository on the record date (usually 7 to 15 days prior to the payout date).

Because the buyer is listed as the registered owner on this date, the issuer deposits the entire gross coupon directly into the buyer's registered bank account via NACH/NEFT. The buyer is now fully made whole for the accrued interest advanced to the seller months earlier.

Tax Implications: Record Dates, TDS, and Capital Gains on Dirty Prices

The interaction between clean price, dirty price, and taxation is one of the most critical aspects for retail participants in India. Errors here can lead to improper reporting in Income Tax Returns (ITR).

The TDS Mismatch Problem

Under Section 193 of the Income-tax Act, 1961, issuers of listed corporate bonds deduct 10% TDS on coupon payouts if the total annual payment to an individual resident exceeds Rs. 10,000 (subject to prevailing thresholds).

Consider our earlier example:

You bought an NCD on October 15, paying Rs. 27.59 per bond in accrued interest to the seller.
On June 30 of the following year, the company distributes the annual coupon of Rs. 95.00.
The company deducts 10% TDS on the full Rs. 95.00 (Rs. 9.50) and deposits the remaining Rs. 85.50 into your bank account.
In your Form 26AS / Annual Information Statement (AIS), the income tax department records gross interest income of Rs. 95.00 against your PAN.

However, you did not earn Rs. 95.00 of interest during that year! You owned the bond for only 259 days; the seller owned it for 106 days. Economically, your true interest income is: Actual Interest Income = Gross Coupon Received (Rs. 95.00) − Accrued Interest Paid (Rs. 27.59) = Rs. 67.41

How Tax Reporting Treats Accrued Interest

Under Indian tax guidelines, interest from bonds is classified under Income from Other Sources and taxed at your applicable marginal slab rates. Two primary accounting approaches exist among chartered accountants regarding accrued interest paid on purchase:

Netting Off Method: The investor reports the gross interest (Rs. 95.00) in Schedule OS, claims the accrued interest paid upfront (Rs. 27.59) as an allowable expense or deduction incurred wholly and exclusively for earning that income, and pays slab tax on the net Rs. 67.41. The full TDS credit (Rs. 9.50) is claimed in the tax return.
Capital Cost Addition Method: Some taxpayers treat the accrued interest paid as part of the total cost of acquisition of the bond. However, when the coupon is received, the full Rs. 95.00 is treated as interest income. When the bond is subsequently redeemed or sold, the higher cost of acquisition reduces the capital gain. This method is generally considered less clean because it converts regular income deductions into deferred capital loss adjustments.

Detailed guidance on tracking these obligations is available in our analysis of bond interest taxation in India. +-------------------------------------------------------------------------+ | THE TAX FLOW ON ACCRUED INTEREST | +-------------------------------------------------------------------------+ Trade Date: Buyer pays Seller: Rs. 1,012 (Clean) + Rs. 27.59 (Accrued) Total Outflow = Rs. 1,039.59

Coupon Date: Issuer pays Buyer: Rs. 95.00 Gross Coupon Less: 10% TDS (Rs. 9.50) Net Bank Credit to Buyer = Rs. 85.50

AIS / Form 26AS: Displays Rs. 95.00 gross income against Buyer PAN.

Net Reality: Buyer's true income = Rs. 95.00 - Rs. 27.59 = Rs. 67.41 Buyer claims credit for entire Rs. 9.50 TDS. +-------------------------------------------------------------------------+

Clean vs Dirty Yield: Why YTM Calculations Demand Dirty Price

Yield to Maturity (YTM) represents the internal rate of return (IRR) of a bond if held until redemption, assuming all coupon distributions are reinvested at the same rate.

A common calculation flaw occurs when investors attempt to calculate yield using the clean price in standard financial formulas:

$$\text{Incorrect Yield Approach} \longrightarrow \text{Plugging clean price as cash outflow at } t=0$$

If you quote an outflow of Rs. 1,012 at time zero, your calculated return will look significantly higher than reality. Because you must actually transfer the dirty price (Rs. 1,039.59) from your bank account on settlement day, the true cash outflow at time zero is the dirty price. True Cash Flow Timeline: Time 0 (Settlement): - Rs. 1,039.59 (Dirty Price paid) Time 1 (First Coupon): + Rs. 95.00 (Full coupon received) Time 2 (Second Coupon): + Rs. 95.00 ... Maturity: + Rs. 1,000.00 (Face value redemption)

Any accurate YTM calculator or pricing engine evaluates cash flows starting from the dirty price settlement. To learn more about navigating these yields across various maturities, see our guide to understanding bond yields and our breakdown of bond yield comparisons.

Common Mistakes Bond Investors Make with Accrued Interest

Even experienced participants in India's debt market occasionally stumble over pricing technicalities. Here are three common pitfalls:

1. Assuming Platform Markup When Invoice Exceeds Quoted Price

Retail investors frequently suspect OBPPs or brokers of tacking on hidden spreads or markups when the checkout invoice exceeds the catalog price. When an order screen shows an extra Rs. 20 to Rs. 60 per bond, check the "Accrued Interest" line item. Regulated SEBI OBPPs are mandated to display an itemized breakdown showing clean price, elapsed accrual days, accrued interest, and statutory exchange charges.

2. Trading Immediately Prior to the Record Date (Cum-Coupon vs Ex-Coupon)

Bond issuers announce a "record date" prior to coupon disbursements. If you trade during the "shut period" or immediately before the record date, clearing delays can create complications:

Cum-Coupon: The bond trades with the right to receive the forthcoming coupon. The buyer pays accrued interest to the seller.
Ex-Coupon: The trade takes place after or right on the cut-off. The seller will receive the upcoming coupon directly from the issuer. In this case, accrued interest calculations reset or can even turn negative in certain institutional convention adjustments.

On Indian retail exchanges, bonds normally shift to ex-coupon status 1 to 2 working days before the record date. Buying during this transition without confirming your entitlement to the registry can cause confusion about who receives the interest payment.

3. Overlooking Accrued Interest When Computing Capital Gains

When selling a bond before maturity, an investor may sell at a total dirty price of Rs. 1,040. If the clean price at sale was Rs. 1,010 and accrued interest was Rs. 30, the investor must ensure that the Rs. 30 interest component is reported as interest income (taxable at slab rates), while the capital gain or loss is calculated strictly using the clean sale price against the clean acquisition cost. Combining interest and principal into a single capital gain figure misrepresents your tax classification.

Frequently Asked Questions

What is the exact formula for clean price and dirty price?

The core relationship is: Dirty Price = Clean Price + Accrued Interest. The clean price is the pure market value of the bond excluding interest. The dirty price (or invoice price) is the total amount paid by the buyer and received by the seller upon settlement.

Why do bond prices drop sharply after a coupon is paid?

Only the dirty price drops sharply. On the day a bond goes ex-coupon, the buyer is no longer entitled to the pending coupon payment. Consequently, the accumulated accrued interest drops to zero. The clean price remains unaffected by this scheduled payment and changes only if underlying market yields or issuer credit fundamentals shift.

Does the buyer or the seller get the coupon if a bond is sold mid-year?

The issuer pays the entire coupon directly to whoever is registered as the bondholder on the official record date (the buyer). However, because the buyer paid accrued interest upfront to the seller upon settlement, both parties economically receive the exact share of interest corresponding to their respective holding periods.

What day-count convention is used for G-Secs versus corporate bonds in India?

Central Government Securities (G-Secs) and State Development Loans (SDLs) use the Actual/Actual convention, where exact calendar days are counted and divided by the actual days in the year (365 or 366). Most Indian corporate debentures (NCDs) also use Actual/Actual or Actual/365, as detailed in each bond's information memorandum.

Is accrued interest subject to Tax Deducted at Source (TDS)?

TDS is not deducted on accrued interest during a secondary market transaction between buyer and seller. However, when the issuer distributes the coupon on the official payment date, it deducts 10% TDS on the entire gross coupon under Section 193. The registered holder receives the TDS certificate and can claim full tax credit against their overall tax liability in their return.

How does T+1 settlement affect accrued interest calculation?

Indian stock exchanges follow a T+1 settlement cycle for bonds. This means that if you execute an order on Monday (Trade Date T), the trade settles on Tuesday (Settlement Date T+1). Accrued interest is calculated up to the calendar day immediately preceding the settlement date (Monday), ensuring the seller receives interest for every single day they funded the asset.

The Bottom Line

The distinction between clean and dirty bond pricing is essential knowledge for navigating India's secondary bond market. Clean prices keep market trends transparent and comparable across different issuers, while dirty prices ensure that settlement cash flows fairly distribute interest between buyers and sellers.

When planning fixed-income investments, remember that your cash outlay at checkout will always equal the dirty price. By accounting for accrued interest, tracking day-count conventions, and maintaining clean tax records, you can trade corporate debentures and government securities without surprises.

Disclaimer: This post is for educational purposes only. BondDekho is not a SEBI-registered investment adviser. Yields and risks mentioned are illustrative; consult a SEBI-registered adviser before making any investment decision.