TBILLEQ Function in ONLYOFFICE Spreadsheet Editor: Syntax and Examples

=TBILLEQ(DATE(2026,1,15),DATE(2026,4,15),0.10) is predicted by the inspected source to return approximately 0.104018238814, or 10.4018238814%. It converts a supplied discount rate using a 365 numerator and an internal day count in the denominator.

The current source does not use the same actual-day path as TBILLPRICE. For these dates it derives 91 internally, while the actual interval is 90 days. Treat the following as source-scoped expectations, not native observations or proof of conformity with a particular bill-market convention.

=TBILLEQ(settlement, maturity, discount)

All arguments are required. The official help defines settlement, maturity within one year and the bill discount rate. Enter a positive annual decimal rate, such as 0.10 for 10%. This rate is measured against redemption and is not already an investment-based yield. The output is a rate, not a price or amount received.

There is no basis argument, coupon frequency, market-convention switch or custom redemption value. Do not invent an optional fourth argument to change its day count.

The source adds one day to maturity, passes the resulting dates to a 360-day helper and calculates 365×discount / (360−discount×n). It rejects n above 360 after computing it.

As in TBILLYIELD, the caller passes zero-based month numbers into a helper expecting one-based month values. Month-end and February handling therefore must not be generalized as standard US30/360. The selected 15th-of-month examples make the traced arithmetic explicit without claiming that all dates follow a simple “actual days plus one” rule.

1. Enter settlement =DATE(2026,1,15) in A2 and maturity =DATE(2026,4,15) in B2.
2. Enter discount 0.10 in C2.
3. Put =TBILLEQ(A2,B2,C2) in D2 and apply percentage formatting.
4. Keep the day-count note with the calculation: the inspected path produces n=91.

Maturity is shifted to April 16 for the helper. The uncomplicated day/month arithmetic gives 3×30+1=91. The expression is 36.5/(360−0.10×91)=36.5/350.9≈0.104018238814.

For January 15–July 15 the traced n is 181, coinciding with the actual-day interval. Agreement on that one case does not validate the path for other dates; January 15–April 15 already shows the discrepancy.

For the main example, the supplied discount rate 10% and calculated equivalent rate approximately 10.4018% are different measures. The denominator adjusts for the discounted purchase base, and the 365 numerator differs from a 360-day annualization. Do not pass the resulting rate back into a discount-rate input as though it were unchanged.

An independent 90-day evaluation of the same algebra would use 36.5/(360−9), which is a different number. Such a comparison can reveal the implementation’s day-count choice, but it does not establish a replacement market formula. Keep the source-derived result separate from any externally specified convention and verify the intended convention before operational use.

The source rejects nonpositive discount, settlement at/after maturity, unsupported date serials and its computed n>360. Dates are floored. Its one-year behavior differs from TBILLPRICE: the shown calendar-year endpoints produce n=361 and fail.

For the intended finite positive result, require 360−discount×n > 0. The wrapper has no explicit positive-denominator guard before division, so this guide does not promise a particular displayed error for a zero denominator or a meaningful interpretation for a negative result from extreme discounts. The worked examples stay well away from that boundary.

No native output, market-feed comparison or regulatory-convention validation is claimed.

Checked October 18, 2026 against the official TBILLEQ help and official SDKJS source tagged v10.0.0.169. Desktop Editors 10.0 was released October 13, 2026. The original introduction version for this individual function is not established; current help does not mark it retired or deprecated.

All results in this guide are expected values from documentation, source inspection and independent arithmetic, not application observations. Neither the application nor its calculation engine was used to test these examples. The tag matches the installed version/build designation but does not establish identical behavior in every older release, mobile client, server deployment or imported workbook. Examples use English names and comma argument separators; adapt separators to editor settings. These fictional calculations explain a function, not an investment or borrowing recommendation.

• DATE
• DAYS