COUPDAYBS in WPS Spreadsheet: Count Accrued Coupon Days
Calculate days from the coupon-period start to settlement, with explicit basis and independently checked calendar examples.
Verification status: See the evidence and test scope described in this guide. How formula examples are checked
Quick answer: COUPDAYBS returns the day count from the start of the coupon period to settlement. With settlement April 20, 2026, maturity November 15, 2027, semiannual coupons and basis 1, the independent regular-schedule expectation is 156 days.
Availability and evidence scope
The official WPS COUPDAYBS lesson documents this function for WPS Office for Windows Personal. The source was checked on October 19, 2026. It does not establish the first release, the last supported release, or an exact installed build. Availability in Mac, Linux, web, mobile and other editions remains unverified.
Examples below distinguish documented behavior from independently calculated controls. No results were captured from a new WPS execution for this guide. No native screenshot or cross-client compatibility test is claimed.
Syntax and arguments
=COUPDAYBS(settlement,maturity,frequency,[basis])
| Argument | Required? | Meaning |
|---|---|---|
settlement |
Yes | Date the buyer acquires the security; use a real spreadsheet date. |
maturity |
Yes | Security’s maturity date, later than settlement. |
frequency |
Yes | Coupon payments per year: 1 annual, 2 semiannual, 4 quarterly. |
basis |
No | Day-count convention; omitted means 0, US (NASD) 30/360. |
The documented basis values are 0 (US/NASD 30/360), 1 (actual/actual), 2 (actual/360), 3 (actual/365), and 4 (European 30/360). Set this explicitly when comparing workbooks. The common examples use basis 1 so the calendar-day arithmetic is transparent. A basis is a financial convention, not a date-display format.
Use DATE rather than ambiguous date text. The official lessons say arguments are truncated to integers; this guide deliberately uses whole-day dates and integer frequency/basis values. Fractional-input validation order and settlement exactly on a coupon date still need target-build testing.
Reproducible input sheet
Enter labels in A1:A4 and these values in B1:B4:
| Cell | Label | Enter |
|---|---|---|
| B1 | Settlement | =DATE(2026,4,20) |
| B2 | Maturity | =DATE(2027,11,15) |
| B3 | Payments per year | 2 |
| B4 | Basis | 1 |
For the independent model, assume a regular semiannual schedule anchored on maturity, with coupons every May 15 and November 15. Around settlement, the previous coupon is November 15, 2025 and the next is May 15, 2026. These deliberately non-month-end dates avoid assuming any special end-of-month roll convention.
Example: calculate and explain the result
=COUPDAYBS(B1,B2,B3,B4)
The expected 156 days is the actual calendar difference from November 15, 2025 to April 20, 2026. It is not the entire coupon period and is not the interval from issuance.
These expectations are calculated from the stated calendar model, not from native WPS execution. The model anchors regular coupons on maturity and steps backward by 12/frequency months. It counts actual date differences without adding an extra day for both endpoints.
Advanced example: audit an accrual fraction
Suppose a regular semiannual coupon is 30 currency units and this model allocates it in proportion to actual elapsed days in the coupon period. Enter 30 in B6, then:
=COUPDAYBS(B1,B2,B3,B4)/COUPDAYS(B1,B2,B3,B4)
The independently calculated fraction is 156/181 = 0.8618784530. For the illustrative allocation:
=B6*COUPDAYBS(B1,B2,B3,B4)/COUPDAYS(B1,B2,B3,B4)
The model gives 25.8563535912, or 25.86 when displayed to two decimals. This is an explicit educational allocation assumption, not a claim that every bond accrues this way. Coupon rate, principal, day-count terms and settlement conventions must come from the actual instrument.
The useful audit is that elapsed and remaining basis-1 days add to the entire period: 156 + 25 = 181. A mismatch often means the formulas reference different settlement dates or basis cells. The count alone is not an interest amount.
Errors, limits and troubleshooting
| Symptom | Documented rule or practical check |
|---|---|
#VALUE! |
The lesson identifies invalid settlement or maturity dates. Replace date text with DATE formulas before investigating the bond calculation. |
#NUM! |
Check that frequency is 1, 2 or 4, basis is within 0–4, and settlement is earlier than maturity. |
| A plausible result differs from another workbook | Compare the actual stored dates, payment frequency and explicit basis, not just the displayed labels. |
| Formula is not recognized | Confirm the function in the target installation; the lesson does not guarantee every build or client. |
A regular coupon calculation does not reconstruct an irregular first or final coupon from issue-date information: there is no issue-date argument here. Nor does the function model business-day holidays, negotiated payment-date adjustments or a changing coupon schedule through the four arguments. Reconcile the assumed schedule with the security’s terms before using the result in a financial model.
Keep basis-1 calendar checks separate from 30/360 checks. Do not treat ordinary date subtraction as a universal substitute for a financial day-count convention. Month ends, leap days, settlement exactly on a coupon date and fractional arguments are useful additional native test cases, but no result for those untested boundaries is asserted here.
Choose the right coupon result
Use this function for elapsed period days. Use COUPDAYS for the entire period and COUPDAYSNC for the remainder. Do not substitute the previous coupon date serial for a day count.
References and verification
- Official WPS COUPDAYBS lesson (Chinese; Windows Personal documentation).
- Official COUPDAYS basis table, used to confirm the shared optional-basis mapping absent from the extracted COUPDAYBS table.
The documentation establishes the syntax and stated behavior. Original examples were checked independently under the assumptions stated alongside them; target-build execution remains a separate check. Version boundaries have not been inferred from another spreadsheet product.