Bond Accrued Interest Calculator
On $100,000 of par at a 4% coupon from August 31 to October 6, 2026, 36 days accrue $400.00 on 30/360. A 98.5 clean price becomes 98.9 ($98,900.00 total).
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Accrued interest, dirty price, and settlement invoice
Accrued Interest
$400.00
Days Accrued (on This Count)
36 days
Accrued Interest per $100 of Par
0.4
Full Price (Clean Price Plus Accrued Interest)
98.9
Principal at the Clean Price
$98,500.00
Total to Pay at Settlement
$98,900.00
One Full Coupon Payment
$2,000.00
How the Days Were Counted
30/360 (MSRB G-33 / FINRA 11620): 36 days of 360-day year
Calendar Days From the Start to Settlement
36 days
Over 36 days accrued (36 calendar days), $100,000 of par at a 4% coupon accrues $400.00 (0.400000 per $100 of par).
With a 98.5% clean price ($98,500.00 principal), the full price is 98.9 and total pay is $98,900.00.
When the next $2,000.00 coupon arrives, the buyer nets $1,600.00 after recovering accrued interest paid.
- days = 36 days (30/360 (MSRB G-33 / FINRA 11620): 36 days of 360-day year)
- principal = $100,000 × 98.5% = $98,500.00
- total = $98,500.00 + $400.00 = $98,900.00
- accrued = $400.00
Accrued interest in dollars by day-count convention
Accrued interest across the coupon period
Accrued interest across par amounts
Across 8 par amounts from $1,000 to $1,000,000, accrued interest scales from $4.00 to $4,000.00.
| Par amount | Accrued interest | Principal | Total to pay |
|---|---|---|---|
| $1,000 | $4.00 | $985.00 | $989.00 |
| $5,000 | $20.00 | $4,925.00 | $4,945.00 |
| $10,000 | $40.00 | $9,850.00 | $9,890.00 |
| $25,000 | $100.00 | $24,625.00 | $24,725.00 |
| $50,000 | $200.00 | $49,250.00 | $49,450.00 |
| $100,000 (closest to your input) | $400.00 | $98,500.00 | $98,900.00 |
| $250,000 | $1,000.00 | $246,250.00 | $247,250.00 |
| $1,000,000 | $4,000.00 | $985,000.00 | $989,000.00 |
Accrued interest by par amount (rows) and coupon rate in percent (columns).
| Par Amount by annual coupon rate | 2% | 3% | 4% | 5% | 6% |
|---|---|---|---|---|---|
| $1,000 | $2.00 | $3.00 | $4.00 | $5.00 | $6.00 |
| $5,000 | $10.00 | $15.00 | $20.00 | $25.00 | $30.00 |
| $10,000 | $20.00 | $30.00 | $40.00 | $50.00 | $60.00 |
| $25,000 | $50.00 | $75.00 | $100.00 | $125.00 | $150.00 |
| $50,000 | $100.00 | $150.00 | $200.00 | $250.00 | $300.00 |
| $100,000 (closest to your input) | $200.00 | $300.00 | $400.00 | $500.00 | $600.00 |
| $250,000 | $500.00 | $750.00 | $1,000.00 | $1,250.00 | $1,500.00 |
| $1,000,000 | $2,000.00 | $3,000.00 | $4,000.00 | $5,000.00 | $6,000.00 |
Accrued interest across coupon rates
Across 8 coupon rates from 1% to 8%, accrued interest moves from $100.00 to $800.00.
| Coupon rate | Accrued interest | One coupon | Full price |
|---|---|---|---|
| 1% | $100.00 | $500.00 | 98.6 |
| 2% | $200.00 | $1,000.00 | 98.7 |
| 3% | $300.00 | $1,500.00 | 98.8 |
| 4% (closest to your input) | $400.00 | $2,000.00 | 98.9 |
| 5% | $500.00 | $2,500.00 | 99 |
| 6% | $600.00 | $3,000.00 | 99.1 |
| 7% | $700.00 | $3,500.00 | 99.2 |
| 8% | $800.00 | $4,000.00 | 99.3 |
Total to pay by coupon rate (rows) and clean price in percent of par (columns).
| Annual Coupon Rate by clean price | 95% of par | 98.5% of par | 100% of par | 102% of par |
|---|---|---|---|---|
| 1% | $95,100.00 | $98,600.00 | $100,100.00 | $102,100.00 |
| 2% | $95,200.00 | $98,700.00 | $100,200.00 | $102,200.00 |
| 3% | $95,300.00 | $98,800.00 | $100,300.00 | $102,300.00 |
| 4% (closest to your input) | $95,400.00 | $98,900.00 | $100,400.00 | $102,400.00 |
| 5% | $95,500.00 | $99,000.00 | $100,500.00 | $102,500.00 |
| 6% | $95,600.00 | $99,100.00 | $100,600.00 | $102,600.00 |
| 7% | $95,700.00 | $99,200.00 | $100,700.00 | $102,700.00 |
| 8% | $95,800.00 | $99,300.00 | $100,800.00 | $102,800.00 |
Accrued interest and settlement invoice across day-count conventions
| Day-count convention | Days counted | Annual divisor | Accrued per $100 | Accrued interest | Full price (% par) | Total settlement invoice |
|---|---|---|---|---|---|---|
| 30/360 (MSRB G-33 / FINRA 11620) | 36 | 360 (twelve 30-day months) | 0.4 | $400.00 | 98.9 | $98,900.00 |
| Actual/Actual (Treasury 31 CFR 356) | 36 | 181 × 2 (181-day half-year) | 0.39779 | $397.79 | 98.89779 | $98,897.79 |
| Actual/360 (Money market) | 36 | 360 (actual calendar days) | 0.4 | $400.00 | 98.9 | $98,900.00 |
| Actual/365 (Fixed 365-day year) | 36 | 365 (actual calendar days) | 0.394521 | $394.52 | 98.894521 | $98,894.52 |
On $100,000 of par at 4%, the 30/360 count yields $400.00 (36 days) while the Treasury Actual/Actual count yields $397.79 (36 days).
Accrual schedule across the current coupon period
| Period milestone | Settlement date | Days accrued | Accrued interest | Clean principal | Total to pay |
|---|---|---|---|---|---|
| Start (0%) | 2026-08-31 | 0 | $0.00 | $98,500.00 | $98,500.00 |
| 1/6 period | 2026-09-30 | 30 | $333.33 | $98,500.00 | $98,833.33 |
| 1/3 period | 2026-10-30 | 60 | $666.67 | $98,500.00 | $99,166.67 |
| Your settlement | 2026-10-06 | 36 | $400.00 | $98,500.00 | $98,900.00 |
| Midpoint (50%) | 2026-11-30 | 90 | $1,000.00 | $98,500.00 | $99,500.00 |
| 2/3 period | 2026-12-30 | 120 | $1,333.33 | $98,500.00 | $99,833.33 |
| 5/6 period | 2027-01-29 | 149 | $1,655.56 | $98,500.00 | $100,155.56 |
| Day before coupon | 2027-02-27 | 177 | $1,966.67 | $98,500.00 | $100,466.67 |
Across the current coupon period, accrued interest rises from $0.00 on the start date to $400.00 at settlement (36 days) and approaches $2,000.00 by the next coupon date.
Published MSRB Rule G-33, FINRA Rule 11620, and Treasury Appendix B benchmarks
| Published example | Accrual dates | 30/360 days | Actual days | 30/360 per $1,000 | Treasury per $1,000 |
|---|---|---|---|---|---|
| MSRB 1982 Letter ($60/yr muni) | 1982-06-15 to 1982-07-01 | 16 | 16 | $2.67 | 2.6087 |
| MSRB 1982 Letter ($60/yr muni) | 1982-06-15 to 1982-09-01 | 76 | 78 | $12.67 | 12.71739 |
| FINRA 11620(b) Feb–Mar ($50/yr corp) | 2025-02-23 to 2025-03-03 | 10 | 8 | $1.39 | 1.10497 |
| 31 CFR 356 App. B Ex. 1 ($67.50/yr note) | 2000-05-15 to 2000-08-15 | 90 | 92 | $16.88 | 16.875 |
| 31 CFR 356 App. B Ex. 2 ($107.50/yr bond) | 1985-07-02 to 1985-11-04 | 122 | 125 | $36.43 | 36.72798 |
| Default Trade ($40/yr bond) | 2026-08-31 to 2026-10-06 | 36 | 36 | $4.00 | 3.9779 |
Published MSRB Rule G-33, FINRA Rule 11620(b), and 31 CFR Part 356 Appendix B cases verified by the calculator's day-count engine.
How it works
When a bond trades between coupon dates, the buyer pays the seller the interest earned since the last coupon. The issuer sends the full next coupon payment to whoever holds the bond on the payment date. As TreasuryDirect explains, "the buyer pays the accrued interest for the days before the issue date and then receives the full six-month interest payment on the next scheduled payment date." The quoted price without interest is the clean price. Adding accrued interest gives the full (dirty) price. To check when a trade settles around weekends and holidays, open the stock trade settlement date calculator.
Municipal and corporate bonds count days on a 30/360 basis. MSRB Rule G-33(e)(i) requires computations "on the basis of a thirty-day month and a three-hundred-sixty-day year". MSRB Rule G-33(e)(ii) gives the formula `Number of Days = (Y2 - Y1) 360 + (M2 - M1) 30 + (D2 - D1)` and changes D2 from 31 to 30 when D1 is 30 or 31, and D1 from 31 to 30. Under MSRB Rule G-33(d)(ii)(A), "Accrued interest shall be truncated to three decimal places, and rounded to two decimal places immediately prior to presentation of total accrued interest amount on the confirmation". The rule rounds up "if the last digit after truncation is five or above". FINRA Rule 11620(b) sets the same 360-day year of 30-day months for corporate bonds.
U.S. Treasury coupon securities use the Actual/Actual basis in 31 CFR Part 356 Appendix B, Section I. Under Section I.D.1, "the purchaser must pay accrued interest from the dated date (or last interest payment date) up to, but not including, the settlement date." Section I.A.2 divides each six-month payment by the exact calendar days in that half-year. Under Section I.D.4, "Accrued interest per $1,000 of par amount is rounded to five decimal places." When a reopening spans two half-years, both parts are added before rounding to five decimals. The tool also includes Actual/360 (Fiscal Service Prompt Payment formula `P(r/360*d)`) and Actual/365 (12 CFR 1030.7(a)(1), "a daily rate of at least 1/365 of the interest rate"). Compare loan per-diem counts in the daily interest calculator.
How 30/360 and Treasury Actual/Actual diverge at month-end and in February
Because 30/360 turns every month into 30 days, it differs from the calendar across a 31-day month or February. FINRA Rule 11620(b) prints an official table of elapsed days: "From 1st to 30th of the same month to be figured as 29 days", "From 1st to 31st of the same month to be figured as 30 days", and "From 1st to 28th of February to be figured as 27 days". Across the end of February, the table states that "From the 23rd of February to the 3rd of March is to be figured as 10 days" even when 8 calendar days pass. When interest starts on the 30th or 31st, FINRA's table adds: "From 30th or 31st to 1st of the next month to be figured as 1 day."
On a Treasury bond or note, the daily rate changes with the length of the six-month period. A February-to-August cycle in a non-leap year has 181 days. Each day earns 1/181 of a half-year coupon. A May-to-November or August-to-February cycle with two 31-day months has 184 days. Each day earns 1/184 of a half-year coupon. Use the date difference calculator to check exact calendar spans between coupon dates.
Reporting accrued interest on Form 1099-INT, Schedule B, and municipal bonds
Trading a bond between coupon dates splits the interest for tax purposes between the seller and the buyer. Under IRS Publication 550, "If you sell a bond between interest payment dates, part of the sales price represents interest accrued to the date of the sale. You must report that part of the sales price as interest income for the tax year in which the bond is sold." Keep that interest separate from your clean principal in the capital gains tax calculator. For a bond bought at original issue discount, check the bond OID accrual calculator.
For the buyer of a taxable bond, IRS Publication 550 states: "When that interest is paid to you on the next interest payment date, treat it as a nontaxable return of your capital investment rather than as taxable interest income. Do not include the accrued interest you paid in your cost basis of the bond." Your broker's Form 1099-INT Box 1 reports the full coupon payment. Publication 550 tells you to list the full Box 1 amount on Schedule B (Form 1040). Then write "Accrued interest" below the subtotal and subtract what you paid the seller. On a municipal bond, Publication 550 notes that "you cannot deduct the accrued interest from taxable interest income, and you do not add the accrued interest to your cost basis in the bond." Check how taxable bond interest affects your tax bill in the federal income tax calculator.
Video walkthrough
A 3½-minute walkthrough of accrued interest on a bond trade: what you pay at settlement, how the days are counted, and what the next coupon pays back.
Read the transcript
What you pay at settlement
0:00 Buy a bond that trades between coupon dates, and the settlement bill on this trade comes to $98,900: more than the quote.
0:09 The extra $400 is the interest built up since the last coupon date.
0:14 The bond's next coupon, its interest payment, pays it back in full.
0:18 The quote is the clean price of $98,500: what the market says the 4% bond itself is worth.
0:26 Add the accrued interest, and the total the buyer has to pay on the settlement date comes to $98,900, which covers the quote and the interest together.
Where the extra interest comes from
0:37 That interest builds up day by day, after the last coupon date.
0:41 The count runs from August 31 to October 6 on this trade.
0:46 It stops there.
0:47 The count includes the bond's last interest payment date.
0:51 The settlement date is not included.
0:53 Here is the coupon period on this trade.
0:56 At settlement, 36 days come to $400.
1:00 The last coupon date shows nothing accrued; by the day before the next coupon, the accrued total is about $1,967, nearly the full coupon.
1:10 Across the coupon period, the accrued interest keeps building toward the full coupon.
1:16 Your settlement lands 36 days into the line, with the rest still to come.
How the bond counts the days
1:21 How those days get counted changes the bill.
1:24 The 30/360 count is what municipal and corporate bonds follow.
1:29 Each month of the coupon period counts alike.
1:32 The 30/360 count gives the year 360 days.
1:36 So one day of this bond is worth about $11, and the days since the last coupon add up to the interest you owe.
1:43 A Treasury bond counts real days instead.
1:47 The same trade on that count comes to about $398, because its half-year really holds 181 days.
1:55 On this trade the 30/360 count comes out higher.
1:59 Match the day-count convention to the bond you buy.
2:02 The same trade on the Treasury pick comes to about $398, so the interest moves with the count.
What the next coupon pays back
2:09 At settlement you front the accrued interest.
2:12 When the next coupon date arrives, the full $2,000 coupon comes to you, so $1,600 of it is yours to keep.
2:21 The part you fronted comes back inside the payment.
Try your own numbers
2:24 Here is a smaller ticket to price: enter $25,000 of par and a coupon rate of 6%.
2:31 Then set the ticket's dates: the last coupon, the settlement, and the next coupon.
2:36 The results follow as you type.
2:39 This trade accrues $150.
2:41 Before closing the page, copy the link.
2:44 It keeps everything you entered, whenever you come back.
Before you trade
2:48 Before the cash moves, check the dates on the ticket: August 31 to October 6.
2:53 Here 36 days of interest have built.
2:56 One wrong date on the ticket moves the bill: one day is worth about $11.
3:01 The day count convention changes the bill.
3:04 The quote leaves out the accrued interest and the $2,000 coupon pays it back.
3:09 Set the dates on your own ticket, then check your own trade at fastcalc.us.
Formula
30/360: days = (Y2 − Y1) × 360 + (M2 − M1) × 30 + (D2 − D1), D1: 31 → 30, D2: 31 → 30 if D1 was 30 or 31 30/360: accrued = par × rate × days ÷ 360, truncated to 3 decimals, rounded to the cent Treasury: accrued per $1,000 = Σ days in each half-year × (500 × rate) ÷ days in that half-year, rounded to 5 decimals Treasury: accrued = par ÷ 1,000 × that figure, rounded to the cent full price = clean price + accrued per $100 of par total = par × clean price ÷ 100 + accrued
Example
Take a $25,000 municipal bond at 6% from June 15, 1982 that settles on September 1, 1982 at 99.2. MSRB's June 2, 1982 letter says this coupon period "would correctly be figured as 76 days". On 30/360, the span is (9 − 6) × 30 + (1 − 15) = 76 days (78 calendar days). Accrued interest is $316.67 (1.266667 per $100). The full price is 100.466667 and total pay is $24,800.00 + $316.67 = $25,116.67.
MSRB's 1982 letter also counts June 15 to July 1, 1982 as 16 days. In Treasury Appendix B Section I.D Example 1, a 6 3/4% note accrues 92 days from May 15 to August 15, 2000 in a 184-day half-year. That is $0.183423913 × 92 = $16.87500 per thousand, or $2,531.25 on $150,000.
In Treasury Appendix B Section I.D Example 2, a 10 3/4% bond dated July 2, 1985 settles on November 4, 1985. That is 125 days accrued before the first coupon on February 15, 1986. The first 44 days accrue $13.06630, and the next 81 days accrue $23.66168. Together they total $36.72798 per $1,000, or $404.01 on $11,000 of par.
Assumptions and limitations
- Four day counts are included: municipal and corporate 30/360 (with no end-of-February exception), U.S. Treasury Actual/Actual for semiannual bonds, money-market Actual/360, and fixed-year Actual/365.
- Interest accrues from the start date you enter up to, but not including, the settlement date. Under MSRB Rule G-33(e)(ii), "time periods shall be computed to include the day specified in the rule for the beginning of the period but not to include the day specified for the end of the period."
- Since May 28, 2024, bond trades settle on T+1 (next business day). FINRA's guide notes that "The T+1 settlement cycle applies to transactions for stocks, bonds, options, municipal securities, exchange-traded funds, certain mutual funds and U.S. government securities, and limited partnerships that trade on an exchange."
- Amounts round to the cent under each convention. On 30/360, dollar interest truncates at the third decimal place before rounding to two decimals. On Treasury Actual/Actual, the five-decimal factor per $1,000 is multiplied by par and rounded half-up to the cent. Positive interest below $0.005 shows as Under $0.01.
- The tool uses the clean price you enter. It does not price cash flows from a yield or adjust for defaulted, flat-trading, or floating-rate bonds.
These figures are estimates for learning and planning, not financial, tax, legal or investment advice. Terms of use.
What to do with the result
Check all three dates on your trade ticket before paying. The start date is the last coupon date (or the dated date for a new issue). The settlement date is when cash and bonds trade hands, and the next coupon date is the first payment after settlement. At the default inputs, a one-day change in settlement shifts the bill by $11.11.
Match the day count to the bond type. Pick 30/360 for municipal and corporate bonds and Actual days for U.S. Treasury coupon securities. On a $100,000 6% bond from July 15 to August 15, 2026, Treasury Actual/Actual counts 31 days ($505.44) while 30/360 counts 30 days ($500.00), a $5.44 gap.
Check intermediate rounding when your ticket differs by a cent. In Treasury Appendix B Section I.A.3, an 8 3/8% note accruing 182 days in a six-month period pays $41.419837 per $1,000, or $828.40 on $20,000 of par. Under FINRA Rule 11620(f), "where the amount of such interest equals or exceeds five mills, it shall be considered as one cent; fractions of a cent less than five mills shall be disregarded."
Keep your purchase confirmation for tax filing so you can subtract accrued interest paid from your broker's interest statement on Schedule B. If you pay $250.00 of accrued interest at settlement and collect a $1,250.00 coupon later that year, subtracting the $250.00 leaves $1,000.00 of net taxable interest.
Frequently asked questions
Why is the accrued interest a few dollars different on the Treasury count?
The 30/360 count treats every month as 30 days. The Treasury counts real days and divides a half-year coupon by the real days in that half-year (181 to 184). Over 36 days on the default $100,000 4% bond, 30/360 gives $400.00 while a 181-day Treasury half-year gives $397.79.
Is accrued interest taxable to the buyer?
No. Under IRS Publication 550, the buyer pays accrued interest to the seller ($400.00 at the default inputs) and recovers it inside the next coupon ($2,000.00). List the full Form 1099-INT Box 1 amount on Schedule B and subtract $400.00 as "Accrued interest" so only $1,600.00 is taxed.
How much interest accrues per day on a $100,000 4 percent bond?
On the 30/360 count it is $100,000 × 4% ÷ 360 = $11.11 a day, so 36 days is $400.00. A full semiannual coupon is $2,000.00, which is 180 of those days.
How many days from the 31st of one month to the 6th of the next?
On 30/360 the start day 31 counts as 30, so August 31 to October 6 is 36 days (it is 36 calendar days too). January 31 to March 6 is 36 days on 30/360 but only 34 calendar days in 2026.
What is the clean price and the full price?
The clean price is the quote without accrued interest. At a clean price of 98.5 and 0.4 of accrued interest per $100 of par, the full price is 98.9, which is $98,900.00 for $100,000 of par.
How do MSRB Rule G-33 and FINRA Rule 11620 round fractions of a cent on bond accrued interest?
Under MSRB Rule G-33(d)(ii)(A), the dollar figure on a municipal bond is truncated to three decimal places first and then rounded to two decimal places. For example, $1,000 at 1.5% for 3 days equals $0.125 and rounds to $0.13, whereas $1,000 at 1.4996% for 3 days equals $0.12497, truncates to $0.124, and rounds to $0.12.
Sources
- U.S. Department of the Treasury, 31 CFR Part 356 Appendix B — Marketable Securities Settlement Formulas (current version)
- Municipal Securities Rulemaking Board, Rule G-33: Calculations (current version)
- Financial Industry Regulatory Authority, Rule 11620: Computation of Interest (page modified May 28, 2024)
- Financial Industry Regulatory Authority, Understanding Settlement Cycles: What Does T+1 Mean for You? (page modified May 7, 2026)
- TreasuryDirect, Understanding Pricing and Interest Rates — Treasury Notes and Bonds (page modified May 15, 2026)
- Internal Revenue Service, Publication 550: Investment Income and Expenses — Accrued Interest on Bonds (page reviewed Apr 30, 2026)
- Bureau of the Fiscal Service, Prompt Payment: Simple Daily Interest (page modified Jun 30, 2026)
- Consumer Financial Protection Bureau, 12 CFR § 1030.7 — Payment of Interest, Regulation DD (current version)
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