TBILLYIELD Function (Gnumeric)

• Introduced: Recorded as implemented in the grouped Gnumeric 0.33, 0.34 and 0.35 release notes. Those notes do not isolate which of the three releases first contained it, so the precise first version and release date remain unestablished.
• Documented support: Registered in Gnumeric 1.12.62, in the Financial Functions plugin. No retirement is established.
• Last functioning version: Unverified for this guide; source presence does not certify an application execution.
• Scope and dates: English formulas are shown. Official source snapshots were retained from the October 13–14, 2026 audit. This full guide and its reference calculations were checked on October 15, 2026; no newer source retrieval or native run is implied.

TBILLYIELD returns (100-price)/price*360/days. It annualizes the gain relative to the amount paid using a 360-day year. This differs from a discount rate expressed relative to face value, and from the 365-day convention used by the inspected TBILLEQ formula. It is a simple annualized yield, not a compounded annual return.

The function-specific help and complete callback provide the product-specific contract.

=TBILLYIELD(settlement,maturity,price)

• settlement: Valid starting date.
• maturity: Later valid date, at most 365 days after settlement.
• price: Positive quoted price per 100 face value. All three arguments are required; no basis argument is available.

The registration was checked alongside the callback; use the exact function name and argument order rather than assuming cross-application equivalence.

Put =DATE(2026,1,1) in B2, =DATE(2026,6,30) in B3 and price 97.5 in B4. Confirm =B3-B2 gives 180. Then =TBILLYIELD(B2,B3,B4) has reference result approximately 0.051282051282, displayed as 5.128205128205%. The intermediate gain is 2.5 and the holding-period return is 2.5/97.5, about 2.564102564103%; multiplying by 360/180 gives the annualized result.

A price quoted for 10000 face value must first be divided by 100 to obtain the per-100 input. Passing a total purchase amount such as 9750 instead of 97.5 changes the calculation completely.

All outputs below are source-derived independent reference results. Decimal outputs are rounded to twelve places where needed. Use DATE expressions as written for date-based examples rather than substituting ambiguous date text.

The price can be recovered from the yield under the same convention: =100/(1+yield*days/360). Using the unrounded reference yield and 180 days reconstructs 97.5. This is a useful cross-check when a spreadsheet imports either prices or yields from a table. Retain enough digits when comparing both directions.

If the price came from a 5% discount rate, then =TBILLPRICE(B2,B3,5%) returns 97.5, while TBILLYIELD gives the higher 5.128205% result. The discount formula uses face value in its denominator; TBILLYIELD uses purchase price. A price of 100 gives zero yield. A price above 100 gives a negative yield rather than automatically failing the source guard.

The callback returns #NUM! if price is zero or negative, days is zero or negative, or days exceeds 365. It accepts exactly 365 days. Unlike TBILLPRICE and TBILLEQ, it does not accept identical settlement and maturity dates because the day count appears in a divisor. Check this difference before assuming that bill functions share one validation policy.

Use valid date cells and inspect their numeric difference. This guide does not certify locale-specific date text or invalid-date coercions. Date conversion is delegated to Gnumeric’s shared helper. The numerical example uses whole dates whose difference is independently known, and no time-of-day result is implied. To display a decimal return as a percentage, change its number format; multiplying by 100 and then formatting as percent would scale it twice.

The fixtures use explicit strings or valid numeric arguments and dates. Native blank/text coercions, localized formula entry and display formatting remain unverified; keep missing inputs distinct from intentional zero.

• Pinned worksheet implementation
• Pinned function help
• Additional helper source

The calculations are an independent reference model, not execution of the full Gnumeric engine, headless application or graphical editor. No exact installed-release behavior, GUI entry, locale handling, import parity or extreme-value outcome is certified beyond the stated source scope. Reproduce a small fixture in the target build before relying on an operational workbook.

TBILLPRICE, TBILLEQ.