Accrued interest
The part of the next coupon a bond has already earned since its last coupon date, which a buyer pays the seller on top of the quoted price.
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How it is computed here
Computed with the actual/actual convention the Treasury uses: the regular coupon of one period times the days since the last coupon date, divided by the days in the current coupon period. It is added to the clean price to give the full price, and the position panel shows it in money for the nominal you hold.
Worked example
- UST 4.625% 2036-08-15 pays 4.625% a year in two coupons of 2.3125 per 100; the last was on 15 Aug 2026 and the next is on 15 Feb 2027, a period of 184 days.
- On 2 Oct 2026, 48 of those 184 days have passed: 2.3125 × 48 ÷ 184 = 0.6033 per 100.
- On 10,000 of face value that is 60.33 USD: already inside the full price, and paid back in the next coupon.
Real Treasuries valued today on the Treasury's par curve: our estimates, not dealer quotes, and no yield here is a return anyone is owed. The demo holds none; signed in with a Treasury of your own, this is worked on yours.
Where it misleads
It is not an extra return: it comes back in the next coupon, which is why the quoted (clean) price leaves it out. A buyer who holds across the coupon date receives the whole coupon, so the interest accrued before the purchase was paid for in the price, not lost.
The formula
- AI — the accrued interest per 100 of face value;
- C — the regular coupon of one period per 100: the yearly coupon divided by two for a Treasury;
- d — the days from the last coupon date to the settlement date;
- D — the days in the current coupon period, from the last coupon date to the next.
A worked example on a real Treasury
The Treasury note UST 4.625% 2036-08-15 pays C = 4.625 ÷ 2 = 2.3125 per 100 every six months. Its last coupon date was 15 August 2026 and the next is 15 February 2027, a period of D = 184 days; settlement on 1 October 2026 is d = 47 days after the last coupon. AI = 2.3125 × 47 ⁄ 184 = 0.5907 per 100. On 10,000 of face value that is 59.07, the interest the seller earned in those 47 days, which the next coupon of 231.25 pays back in full to whoever holds the bond on 15 February 2027.
What this page does not do
It is a convention for splitting a coupon between seller and buyer. It does not depend on the price or on the yield, and it says nothing about the value of the bond itself.
Compared with
- Clean and full price — the clean price and the full price it completes
- Yield to maturity — the yield solved from the full price
Questions people ask
Is accrued interest a cost?
No. The buyer pays it with the price and receives it back in the next coupon, in full. It only reflects that the coupon covers a period of which the seller held the bond for part.
Why is the quoted price lower than what a buyer pays?
Quoted prices are clean prices: they leave the accrued interest out so the price does not jump by a coupon every six months. What a buyer pays at settlement is the full price: the clean price plus the accrued interest.
Sources
Last reviewed 2026-10-02 by Sphinx Risk.