Accrued Interest

In formula terms:

Accrued Interest = Face Value × Coupon Rate × (Days Since Last Payment ÷ Days in Coupon Period)

The number of days used depends on the applicable day count convention. The face value is typically the principal amount of the bond (often 1,000 in many markets), and the coupon rate is the annual interest rate stated on the bond. Because most bonds pay interest semi-annually, the formula is frequently applied to half of the annual coupon rate over a roughly 180-day period, though the exact period length depends on the specific day count convention governing the security.

For instance, consider a bond with a face value of 1,000 and a 6% annual coupon paid semi-annually. Each payment equals 30. If the bond is sold halfway through a 90-day period (after 45 days), the accrued interest would be:

30 × (45 ÷ 90) = 15

This amount is paid by the buyer to the seller at the time of the transaction. Note that the 90-day period in this simplified illustration is shorter than the roughly 180 days that would apply under a full semi-annual coupon period; in practice, the exact number of days in the coupon period is determined by the day count convention, discussed further below.

Accrued Interest in Bond Transactions

Bonds are typically traded between coupon payment dates. The quoted price in the market—known as the clean price—does not include accrued interest. However, the total amount the buyer actually pays, called the dirty price (or invoice price), includes accrued interest.

Dirty Price = Clean Price + Accrued Interest

This system ensures fairness. Since the next full coupon payment goes entirely to the bondholder on record at the payment date, the seller must be compensated for the time they held the bond since the last payment. Without this adjustment, trading behavior would become inefficient, with sellers waiting until after coupon dates and buyers avoiding purchases before them.

From the buyer's perspective, the accrued interest paid is not an additional expense—it is effectively reimbursed when the full coupon is received. Only the portion corresponding to the buyer's holding period represents true income.

Quoting bonds on a clean-price basis also serves a practical purpose for the market: it allows dealers and investors to compare prices across bonds and across time without the comparison being distorted by where each bond happens to sit within its current coupon period. If bonds were quoted on a dirty-price basis, the quoted price would rise steadily and mechanically as each coupon period progressed, even if nothing about the underlying credit or interest rate environment had changed, making price comparisons far less meaningful. The settlement process itself typically separates the trade date, when the price is agreed, from the settlement date, when the dirty price—including accrued interest—actually changes hands.

The Role of Day Count Conventions

Day count conventions determine how time is measured for interest calculations. Different markets and instruments use different standards, and the choice of convention can materially affect the precise accrued interest figure even when the face value, coupon rate, and calendar dates are identical.

Actual/Actual: Uses the exact number of days in both the numerator and denominator; common for government securities such as Treasury notes and Treasury bonds, where precision in day counting is treated as important enough to track the calendar exactly rather than rely on a simplifying assumption.

30/360: Assumes each month has 30 days and each year has 360 days; widely used for corporate and municipal bonds. This convention simplifies calculations and produces identical accrued interest for any given number of elapsed months, regardless of whether those months actually contained 28, 30, or 31 calendar days.

Actual/360: Counts actual days elapsed but divides by 360; often used in money market instruments and short-term lending arrangements, where the 360-day year is a long-standing banking convention.

Actual/365: Uses actual days over a 365-day year; common in some international markets, including certain sterling-denominated instruments.

These conventions can slightly affect the accrued interest calculation, and the difference between them becomes more pronounced the longer the holding period or the larger the face value involved. Because the applicable convention is fixed by the terms of the security rather than chosen by the buyer or seller, market participants must know which convention governs a given bond before they can independently verify a quoted dirty price. Mismatched assumptions about day count convention are a recurring source of small reconciliation discrepancies between counterparties' back-office systems, even though the underlying trade terms are identical.

Accrued Interest on the Balance Sheet

In accounting, accrued interest appears as either:

Accrued interest receivable (asset): Interest earned but not yet collected. A lender or bondholder records this amount as a current asset, reflecting the economic reality that the interest has already been earned even though the cash has not yet arrived.

Accrued interest payable (liability): Interest incurred but not yet paid. A borrower or bond issuer records this amount as a current liability, reflecting an obligation that has already accumulated even though no payment has yet been made.

Under accrual accounting principles, interest must be recorded in the period it is earned or incurred, regardless of when the payment is actually made. In practice, this means that at each reporting period end, an adjusting journal entry recognizes the interest that has accumulated since the last payment date. For a holder of the bond, this typically takes the form of a debit to accrued interest receivable and a credit to interest income; for the issuer, it takes the form of a debit to interest expense and a credit to accrued interest payable. When the coupon payment is eventually made, the accrued interest balance is reversed and cash changes hands for the full coupon amount. This treatment ensures that a company's financial statements reflect economic performance during the period in which it actually occurred, consistent with the broader principles of accrual accounting rather than simple cash-basis bookkeeping.

Accrued Interest from the Issuer's Perspective

For the bond issuer, accrued interest represents a growing obligation between coupon dates. Each day increases the amount owed to bondholders. This obligation is recorded as a liability and is settled when the coupon payment is made. From a cash management perspective, issuers often need to plan for the timing mismatch between when interest expense accrues on their books and when the actual cash coupon payment is due, particularly for issuers with multiple bond series outstanding with staggered payment dates.

Accrued Interest vs Accrued Income

Accrued interest is a specific type of accrued income. While accrued income includes all earnings recognized before cash receipt (such as rent or fees), accrued interest refers strictly to interest-related earnings or expenses. Accrued rent, for example, arises when a tenant has used a leased property during a period but has not yet paid the rent invoice, while accrued fees might arise when a service has been rendered but not yet billed.

Dividends occupy a related but distinct category: unlike interest, dividends are not earned continuously over time and are not accrued on the books of the recipient until the dividend has actually been declared by the issuing company's board, at which point a dividend receivable is recognized rather than an amount that accumulates gradually day by day. This distinction—between continuously accruing interest and discretely declared dividends—is a frequent point of confusion for those newer to fixed income and equity accounting alike.

Tax Treatment of Accrued Interest

Tax handling depends on the accounting method used:

Cash-basis taxpayers (most individuals): Recognize interest income when it is received. However, accrued interest paid at purchase reduces taxable income because it is included in the first coupon received but does not represent earned income. In practice, a buyer who purchases a bond between coupon dates and pays accrued interest to the seller can generally report that payment as an offset against the interest income reported when the next full coupon is received, rather than treating the entire coupon as taxable income to the buyer.

Accrual-basis taxpayers (typically corporations): Recognize interest as it accrues over time, regardless of payment timing, consistent with the same accrual principle that governs their financial statement reporting.

Accrued interest paid on the purchase of a bond should not be confused with two related but distinct concepts: original issue discount, which arises when a bond is issued below its face value and must be accreted into taxable income over the life of the bond even though no cash is received until maturity, and market discount, which arises when a bond is purchased in the secondary market below its adjusted issue price and is generally taxed as ordinary income upon disposition or maturity rather than as capital gain. 

For municipal bonds, accrued interest paid by the buyer at purchase is typically treated the same way as it would be for a taxable bond—as an offset to the next interest payment received—even though the underlying coupon interest itself may be exempt from federal income tax.

Accrued Interest Across Different Debt Instruments

Not every debt instrument generates accrued interest in the same way. Zero-coupon bonds, for example, do not make periodic cash interest payments at all; instead, the return to the investor comes entirely from the difference between the discounted purchase price and the face value received at maturity. Rather than accruing cash interest, a zero-coupon bond accretes original issue discount, which must generally be recognized as taxable income each year even though no cash interest is ever paid before maturity. 

Short-term money market instruments such as Treasury bills are similarly issued at a discount to face value rather than carrying a stated coupon, so the concept of accrued interest in the traditional coupon-bond sense does not apply to them in the same way.

Treasury bonds and notes typically use the Actual/Actual day count convention described above, while most corporate bonds and municipal bonds use the 30/360 convention. Floating rate notes present an additional layer of complexity, since the coupon rate itself resets periodically based on a reference rate; accrued interest on a floating rate note is calculated using the rate currently in effect for the applicable period, meaning the dollar amount of accrued interest per day can change from one reset period to the next even though the face value and general calculation structure remain the same. Understanding which instruments accrue cash interest, which accrete discount instead, and which day count convention applies to each is an important part of correctly pricing and settling a trade in the fixed-income market.

Accrued Interest in Practice: Example

Suppose an investor buys a bond with:

Face value: 10,000

Coupon rate: 5%

Payment dates: January 1 and July 1

The investor purchases the bond on March 1, which is 60 days into the coupon period. Using a 30/360 convention, the total period is 180 days.

The semi-annual coupon is:

10,000 × 5% ÷ 2 = 250

Accrued interest:

250 × (60 ÷ 180) = 83.33

The buyer pays this amount in addition to the bond's clean price. On July 1, they receive the full 250 payment, of which 83.33 is simply reimbursement, and the remaining 166.67 is actual earned income. This example illustrates why the buyer is not harmed by paying accrued interest at purchase: the payment is fully returned as part of the next coupon, and only the interest earned during the buyer's actual holding period represents new income.

Common Points of Confusion

Several aspects of accrued interest frequently trip up newer market participants and exam candidates alike. One common error is assuming that the clean price quoted on a trading screen represents the full amount that will change hands at settlement, without accounting for the accrued interest that must be added to arrive at the dirty price actually invoiced. Another frequent point of confusion involves day count conventions: because 30/360 and Actual/Actual can produce different accrued interest figures for the same bond and the same holding period, comparing calculations across instruments without first confirming which convention applies can lead to reconciliation errors. Finally, some investors mistakenly treat the accrued interest they pay at purchase as a sunk cost or additional expense, when in fact it is fully recovered through the next coupon payment and does not represent a net cost of the investment.

Examination Relevance and Key Takeaways

Accrued interest is a heavily tested concept across securities licensing examinations because it sits at the intersection of bond pricing, accounting, and taxation. Candidates should be comfortable computing accrued interest using the standard formula, identifying which day count convention applies to a given category of bond, and distinguishing between the clean price and the dirty price in a bond transaction. The relationship between accrued interest and the buyer-pays-seller settlement mechanism is a frequently tested application, as is the distinction between accrued interest paid at purchase and the taxable interest income ultimately reported when the coupon is received.

The key points to retain are these. Accrued interest is the interest that has accumulated since the last coupon payment but has not yet been paid in cash, and it reflects the accrual method of accounting rather than a cash-basis approach. When a bond trades between coupon dates, the buyer compensates the seller for this accumulated amount, which is added to the clean price to produce the dirty price actually paid at settlement. 

Day count conventions—Actual/Actual for many government securities, 30/360 for most corporate and municipal bonds, and Actual/360 or Actual/365 in certain money market and international contexts—determine precisely how the accrued interest figure is calculated and can produce different results even for economically similar bonds. On the balance sheet, accrued interest is recognized as a receivable for holders and a payable for issuers, consistent with accrual accounting principles. 

For tax purposes, accrued interest paid at purchase offsets the interest income recognized when the next coupon is received, and it should not be confused with original issue discount or market discount, which follow different tax rules. Zero-coupon bonds and discount money market instruments do not generate accrued interest in the traditional sense, instead accreting discount over their life. Taken together, these principles explain why accrued interest matters not just for pricing individual trades, but for accurate financial reporting and correct tax treatment across the fixed-income market as a whole.