COUPDAYBS in Collabora Office: Count Days Accrued in the Current Coupon Period
Calculate Collabora COUPDAYBS from the preceding coupon to settlement, audit a regular schedule, and distinguish elapsed days from a coupon-period denominator.
Verification status: See the evidence and test scope described in this guide. How formula examples are checked
Quick answer: =COUPDAYBS(DATE(2001;1;25);DATE(2001;11;15);2;3) has documented result 71. It counts days from the beginning of the coupon period containing settlement to the settlement date.
Syntax and inputs
=COUPDAYBS(Settlement; Maturity; Frequency [; Basis])
Settlement is the purchase/settlement date. Maturity is the date the security expires. Frequency is required and must be 1, 2, or 4. Basis optionally selects the day-count convention; the default is zero.
| Basis | Documented day-count convention |
|---|---|
| 0 or omitted | US NASD, twelve 30-day months |
| 1 | Actual days in months and actual days in the year |
| 2 | Actual days in months, 360-day year |
| 3 | Actual days in months, 365-day year |
| 4 | European method, twelve 30-day months |
Use explicit date values, preferably DATE formulas, rather than ambiguous date-looking text. Frequency is a number of payments per year, not a number of months: 1, 2, and 4 mean annual, semiannual, and quarterly payments. Monthly frequency 12 is outside the stated contract.
The function has no issue-date, first-coupon, coupon-rate, price, or principal argument. It returns a day count, not an interest amount. The examples use regular coupon schedules anchored to maturity and avoid exact coupon-date boundaries and unusual month ends.
Example: reproduce the documented 71-day control
Enter these inputs:
| Cell | Input |
|---|---|
| A2 | =DATE(2001;1;25) |
| B2 | =DATE(2001;11;15) |
| C2 | 2 |
| D2 | 3 |
In E2 enter =COUPDAYBS(A2;B2;C2;D2). The vendor gives 71. For the regular semiannual schedule, the previous coupon date is 2000-11-15, and the next is 2001-05-15.
An independent date subtraction, =A2-DATE(2000;11;15), gives 71 actual days, agreeing with the documented basis-three result. The count is not the 294-day span from settlement to maturity, and it is not the number of remaining payments.
Example: a contemporary regular schedule
Set A5 to =DATE(2026;10;17), B5 to =DATE(2028;1;15), C5 to 2, and D5 to 3. In a regular semiannual schedule, the surrounding coupon dates are 2026-07-15 and 2027-01-15.
=COUPDAYBS(A5;B5;C5;D5) has documentation-based independent expectation 94, verified by subtracting July 15 from October 17. This is an independently constructed schedule calculation, not a native Collabora observation.
Keep the previous-coupon date as an audit column if the count feeds an accrual model. A correct day difference from an incorrect schedule date still produces a misleading result.
Advanced example: an accrual numerator is not the entire model
Suppose a hypothetical coupon payment is 30 and a model uses a 365/2 coupon-period denominator under basis three. For the documented 71-day example, the arithmetic fraction is =71/(365/2), approximately 0.389041096, and the corresponding modeled amount is =30*71/(365/2), approximately 11.671232877.
Those formulas demonstrate how a day count may be used. They do not establish a security’s contractual accrual rules or a clean/dirty price. COUPDAYBS itself supplies neither the coupon amount nor the denominator choice.
The related vendor COUPDAYS example gives 182.5 for that basis-three semiannual period, while COUPDAYBS and COUPDAYSNC give 71 and 110. Their actual-day sum is 181, not 182.5. Do not force every coupon helper into an identity that mixes actual days with a convention-defined denominator.
Advanced audit: separate period and calendar checks
For the newer schedule, the actual surrounding interval has 184 days, split into 94 elapsed and 90 remaining. Adding 94 and 90 is a calendar audit. Dividing 365 by two gives 182.5, a different convention-based period measure.
SUM can combine audit components, and ROUND can format an eventual reporting amount. Neither operation chooses the correct contractual basis for you.
Errors and limitations
Check that settlement precedes maturity, the frequency is 1, 2, or 4, and Basis is a documented value. The dedicated section does not enumerate all native errors, coercions, month-end rules, or settlement-exactly-on-coupon behavior; these are not certified here.
Irregular first or last coupon periods cannot be fully described by this function’s arguments. Do not supply an issue date in place of maturity or assume it automatically knows a special coupon schedule. The exact source example and the regular-date independent controls define this guide’s evidence scope.
Availability and verification
The exact function is documented in Collabora Office 26.04 desktop help, retrieved and reviewed on October 17, 2026. This establishes a documentation scope, not the first release that introduced the function or the last version in which it works; those versions and any retirement date remain unestablished. Collabora Online and mobile support are not inferred from desktop help, nor is behavior in another spreadsheet product.
The examples are documentation-based expectations with independent calculations. They have not been executed in Collabora Office. No application screenshot or native error/coercion certification is implied. Formulas use English function names and semicolon argument separators.
References
- Collabora Office 26.04: COUPDAYBS (checked October 17, 2026).
- Editorial testing standards.