Two prices for one instrument
The clean price excludes accrued interest. The full price, traditionally called the dirty price, consists of the clean price plus accrued interest.[5](#source-market-accrued) The word “dirty” here does not describe the quality of the bond or bad faith in the transaction. It simply names the amount that includes the already accumulated part of the interest payment. Commissions and other costs may be charged separately. If an application shows the total amount to be debited, determine what it includes: clean price, accrued interest, an intermediary fee or another payment. These are different elements and should not be merged into one unexplained percentage.
When a quote is given as a percentage of par, first convert it into money using the correct basis, and only then add accrued interest. With amortization of par, the basis may differ from the original amount. Coupon terms can also change by period.[9](#source-market-corporate-bonds) A calculation based on an old card or a rounded percentage may therefore differ from the actual debit. Checking starts with units: monetary accrued interest per bond cannot be added blindly to a quote expressed as a percentage. Then account for the number of bonds, lot size and transaction costs.
Example of allocating a coupon
Educational hypothetical example: the coupon is set at 60 roubles per period of exactly 180 educational days. For clarity, assume linear daily accrual and that the purchase occurs after 45 such days. Accrued interest equals 60 × 45 / 180 = 15 roubles. If the clean price of one bond is 1,940 roubles, the full price is 1,955 roubles before commission. The parameters are invented solely for the exercise; actual accrual may use a different day-count basis, rounding, settlement date or issue terms.
Continue the same educational hypothetical example: the buyer receives the next full coupon of 60 roubles. But 15 roubles was already paid to the previous holder at purchase. The coupon component after compensating for accrued interest is 60 − 15 = 45 roubles before costs and taxes. This is not the full investment result: changes in clean price, future payments and possible redemption remain. The previous holder received the accrued part from the buyer in the settlement amount, not from the issuer on the coupon date. That distinction removes the illusion of a free nearby coupon.
Trade date and settlement date
Accrued interest is tied to accrual rules and the settlement date, not necessarily to the moment when a person saw the price on screen. The amount may therefore change between viewing the instrument card and execution. Establish which date the displayed accrued interest refers to and which date is used for the actual settlement. Do not automatically apply the number of calendar days since purchase to every bond: issues differ in calendars and formulas. The Moscow Exchange source explains the general mechanism for adding accrued interest, but its educational example does not replace the official terms of a particular bond.[5](#source-market-accrued)
After a coupon payment, accrual for the next period usually starts again under the issue terms. This is not a standalone loss of capital: a proper analysis considers the coupon received and the full price together. A mental counterexample to reading a chart without payments: the full valuation falls by the distributed coupon while a corresponding payment appears in cash receipts. Looking at only one side can call a technical change a loss or, conversely, call the entire payment profit. Simple accounting of “what left, what arrived and what remains” protects against both errors.
Accrued interest does not insure payment
Calculated accrual does not prove that the issuer can transfer the coupon. Credit risk remains: payment may be delayed or may not occur.[8](#source-market-bond-risks) For non-standard issues, separately establish how accrual and the transfer of the coupon right work. Tax treatment of accrued interest also cannot be derived from the educational cash difference; it depends on applicable rules and transaction circumstances. Responsible checking includes the issue documents, settlement date, clean and full prices, transaction costs and confirmation of the right to payment. Understanding these elements does not imply advice to buy before a payment or sell immediately afterward.