TBILLEQ Function in Microsoft Excel: Syntax, Examples & Troubleshooting
Convert a short-term Treasury-bill discount quotation to bond-equivalent yield in Excel with TBILLEQ. Work through 90-day and 30-day examples and distinguish quotation conventions.
Verification status: See the evidence and test scope described in this guide. How formula examples are checked
Quick answer: TBILLEQ returns a Treasury bill’s bond-equivalent yield from its discount quotation. For the short-term examples below, the documented equation is 365×discount / (360−discount×days). It is not the same number as the input discount rate.
Syntax and required inputs
=TBILLEQ(settlement, maturity, discount)
All three arguments are required. Settlement is the buyer’s settlement date, maturity is the bill’s maturity date, and discount is the annual discount quotation, entered as a decimal or percentage. The function returns a rate.
Both date arguments should be real Excel dates or DATE formulas. Microsoft documents truncating settlement and maturity to integers, so a time component does not create a fractional trading day. There is no basis argument in this function; do not append one copied from a different security function.
For the examples, enter =DATE(2026,1,15) in B2 and =DATE(2026,4,15) in B3. The ordinary date difference is 90 days. This short, fixed interval makes the example independently reproducible without a changing current-date input.
Worked example: 8% discount over 90 days
- Enter 8% in B4.
- Enter
=TBILLEQ(B2,B3,B4)in D2. - Expected result: approximately 0.08276643991, or 8.276643991%.
- Compare with
=365*B4/(360-B4*(B3-B2))for this short-term fixture.
The independent arithmetic is 29.2/352.8. The associated discount price is 98 per 100, and the same result follows from 2/98*365/90. Using 365 in that annualization makes it different from a 360-day price-based yield.
Second example: a 30-day bill
=TBILLEQ(DATE(2026,1,15),DATE(2026,2,14),6%)
Expected result: approximately 0.06113902848, or 6.113902848%. The interval is 30 days. The independent equation is 365*0.06/(360-0.06*30).
Its associated price is 99.5. The holding-period price return, 0.5/99.5, multiplied by 365/30 gives the same short-term bond-equivalent result. Do not simply multiply the discount by 365/360 and omit the price adjustment in the denominator.
Advanced application: reconcile different rate columns
For the 90-day example, preserve three separate labels in an analysis sheet:
| Measure | Independently calculated figure |
|---|---|
| Annual discount quotation | 8% |
| Price-based 360-day annualized yield | 8.163265306% |
| Short-term bond-equivalent yield | 8.276643991% |
The cash flows can be identical even when these rates differ. Comparing one security’s discount quotation against another’s bond-equivalent rate without conversion produces an inconsistent ranking.
The equation and examples reviewed here provide short-term arithmetic controls. They do not establish native Excel behavior for every longer-term boundary or alternative market quotation practice. In particular, do not use these examples as proof that an independent short-bill equation reproduces all longer-maturity bond-equivalent conventions. Verify a longer-term production case against the intended Excel build and security terms.
Troubleshooting and documented domain
Microsoft documents #VALUE! when either date is invalid. #NUM! is documented for a zero or negative discount, settlement later than maturity, or maturity more than one year after settlement. The article’s settlement comparison is strictly greater-than; equality behavior has not been natively tested here.
The page describes a 360-day year basis in its DSM wording while using 365 in the numerator of its equation. The short worked fixtures use ordinary actual calendar-day differences and explicitly show both constants. They do not introduce a configurable basis argument, because the syntax has none.
Check that 8% was not entered as 8, that the two dates are valid and ordered, and that the result is formatted as a percentage. A malformed or extreme input can undermine the equation’s denominator. This guide demonstrates formula mechanics and is not advice about purchasing a bill.
Compatibility and verification
Microsoft’s reference checked on October 17, 2026 lists: Excel for Microsoft 365 Excel for Microsoft 365 for Mac Excel 2024 Excel 2024 for Mac Excel 2021 Excel 2021 for Mac Excel 2019 Excel 2016. This current support list does not establish the first release. The introduction version and last functioning version have not been established from the reviewed documentation. No retirement is asserted.
Example verification: Expected numerical results are independently calculated; text and shape expectations follow the documented contract. These examples have not been tested in Microsoft Excel. No screenshot or native execution is claimed.
Related guides and source
DATE in Excel | DAYS in Excel | ROUND in Excel
- Microsoft TBILLEQ reference, retrieved October 17, 2026.