A bond shows a price of 102.40. The settlement statement arrives asking for more than that, and nothing has gone wrong.
Bond markets quote one number and settle on another. The gap is accrued interest, the portion of the next coupon that the seller earned by holding the bond since the last payment date, and it transfers to them as part of the purchase.
The convention is universal, the arithmetic is straightforward, and it surprises almost every first-time buyer because equity markets work nothing like this.
Where This Shows Up When Buying
Most guidance on how to buy bonds covers issuer selection, maturity and credit quality. The mechanics of what leaves the account get less attention.
Three figures matter and they are not the same:
Only the third determines the cash requirement. Budgeting from the first is how people end up short at settlement.
What Accrued Interest Compensates
The logic is one of fairness between buyer and seller rather than a charge of any kind.
A bond earns interest continuously and pays it in lumps, typically twice a year. If a seller has held the bond for four months of a six-month coupon period, they have earned four months of interest that the issuer will pay in full to whoever holds the bond on the payment date.
The buyer therefore compensates the seller upfront and receives the entire coupon later. Training material on the calculation describes the mechanics plainly: to arrive at the quoted figure, you first determine the accrued interest and then subtract it from the dirty price, calculating the accrued interest by multiplying the coupon rate by the fraction of the year that has passed since the last coupon payment.
Nothing is gained or lost by either party. The money simply moves at a different time than the coupon does.
Why Markets Quote the Clean Price
The reason for quoting the smaller number is practical rather than cosmetic.
Accrued interest rises every day through a coupon period and resets to zero the moment the coupon pays. A price including it would climb steadily, then drop sharply on each payment date, producing a sawtooth pattern that has nothing to do with how the market values the bond.
Stripping it out leaves a price that moves only on yield and credit, which is what makes two bonds with different coupon dates comparable at all.
For a zero-coupon bond the distinction disappears entirely, since there is no coupon to accrue and the two prices are identical by definition.
Day Count Conventions
The one complication is that markets disagree on how to count days:
The differences are small per bond and matter at size. They also explain why two calculators can disagree on the same trade, and why the prospectus rather than a general rule determines which applies.
Reading the Quote Itself
US government securities add a further convention that catches people out.
An explanation of bond quoting notes that a Treasury quote of 99-16 does not mean $99.16, but 99 and 16/32nds percent of par, which equals $995.00 per $1,000 face value, a convention that exists because the market is large enough to need very small price increments.
The same source sets out the practical consequence of confusing the two price types: on a quote of 102.40, an investor budgeting $1,024 per bond can face a settlement figure meaningfully above that once accrued interest is added.
It also notes that pricing transparency improved considerably once trade reporting was introduced in the corporate bond market, though that transparency only helps an investor who can interpret what the screen is showing.
What to Check Before Settlement
A short list prevents the common surprises:
The final point is the least known. Close to a coupon date, some markets stop passing the payment to the buyer, and the accrued figure can be negative as a result.
What This Doesn’t Change
None of this affects the return on the bond. Accrued interest is a timing transfer between two parties, not a cost, and it washes out at the first coupon.
What it changes is the cash needed on settlement day and the accuracy of any comparison built on quoted prices. An investor comparing two bonds on clean price is comparing them correctly. One budgeting from clean price is budgeting incorrectly, and the difference lands a few days later.
