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TBILLEQ Function
Summary
The TBILLEQ function calculates the bond-equivalent yield for a Treasury bill based on its settlement date, maturity date, and discount rate. This conversion standardizes Treasury bill yields for comparison with other fixed-income securities using a 365-day year convention.
Syntax
TBILLEQ(settlement, maturity, discount)Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
| settlement | Date |
Yes | Settlement date of the Treasury bill (use DATE function) |
| maturity | Date |
Yes | Maturity date of the Treasury bill (use DATE function) |
| discount | Number |
Yes | Discount rate as decimal (e.g., 0.0914 for 9.14%) |
Using the TBILLEQ Function
TBILLEQ standardizes Treasury bill yields for apples-to-apples comparison with other bonds. Treasury bills quote discount yields using a 360-day year, while coupon bonds use semi-annual 365-day yields. TBILLEQ converts the discount yield to match bond conventions.
Common TBILLEQ Examples
Basic Treasury Bill Yield Conversion
=TBILLEQ(DATE(2008,3,31),DATE(2008,6,1),0.0914)Converts a 9.14% discount rate T-bill maturing June 1, 2008 (settled March 31) to bond-equivalent yield of 9.42%
Using Cell References
=TBILLEQ(A2,A3,A4)References settlement date in A2, maturity in A3, discount rate in A4
Frequently Asked Questions
Common Errors and Solutions
#NUM! error
Cause: Discount rate ≤ 0
Solution: Enter positive discount rate (e.g., 0.05 for 5%)
#NUM! error
Cause: Settlement > maturity or maturity > 1 year after settlement
Solution: Verify dates are in correct chronological order within 1-year limit
#VALUE! error
Cause: Invalid date format
Solution: Use DATE function: DATE(2023,12,31)
#NUM! error
Cause: Days between dates exceed T-bill limits
Solution: Ensure maturity is within 1 year of settlement
Notes
- Formula: TBILLEQ = (365 × discount) / (360 - (discount × DSM)) where DSM = days from settlement to maturity
- Excel stores dates as serial numbers (Jan 1, 1900 = 1)
- Always format result as percentage for readability
- T-bills have maturities from a few days to 1 year
- Use TBILLPRICE and TBILLYIELD for complete T-bill analysis
Compatibility
Available in: Excel 2007, Excel 2010, Excel 2013, Excel 2016, Excel 2019, Excel 2021, Excel 365
Not available in: Excel 2003, Excel XP, Excel 2000, Excel 97
Content last reviewed: December 9, 2025
Update frequency: As needed
Excel versions tested: Excel 2007+