Quick Navigation

DISC Function

Excel 2007+

Summary

The Excel DISC function calculates the annual discount rate for a security that pays interest at maturity, based on its settlement date, maturity date, price, and redemption value. It's essential for analyzing discount securities like Treasury bills.

Syntax

DISC(settlement, maturity, pr, redemption, [basis])

Parameters

Parameter	Type	Required	Description
settlement	`Date`	Yes	Security's settlement date - when the security is traded to the buyer
maturity	`Date`	Yes	Security's maturity date - when the security expires
pr	`Number`	Yes	Price per $100 face value of the security
redemption	`Number`	Yes	Redemption value per $100 face value paid at maturity
basis	`Number`	No	Day count basis (0=30/360 US, 1=Actual/actual, 2=Actual/360, 3=Actual/365, 4=30/360 European)

Using the DISC Function

DISC is used by financial analysts to determine the effective discount rate of securities purchased at a discount and redeemed at face value at maturity. It's commonly applied to Treasury bills, commercial paper, and other short-term discount instruments.

Common DISC Examples

Basic Treasury Bill Discount Rate

=DISC(DATE(2018,7,1), DATE(2048,1,1), 97.975, 100, 1)

Calculates discount rate for a Treasury bill bought at $97.975 per $100 face value using actual/actual day count. Result: 0.001038 (0.1038%)

Commercial Paper Analysis

=DISC(A2, B2, C2, 100, 0)

Calculates discount rate for commercial paper using US 30/360 convention where A2=settlement date, B2=maturity date, C2=price per $100

Short-term Discount Note

=DISC(DATE(2023,1,15), DATE(2023,6,15), 98.5, 100)

90-day discount note discount rate using default basis (US 30/360)

Frequently Asked Questions

DISC works with any discount security like Treasury bills, commercial paper, certificates of deposit, and other instruments bought at discount and redeemed at face value.

Different basis values reflect industry conventions: 0 for corporate bonds (30/360), 1 for government securities (actual/actual), ensuring accurate yield comparisons.

DISC returns #NUM! error since settlement must be before maturity.

Common Errors and Solutions

#VALUE! Error

Cause: Settlement or maturity dates are invalid or entered as text

Solution: Use DATE() function or ensure cells are formatted as dates

#NUM! Error - Negative Values

Cause: Price (pr) or redemption ≤ 0

Solution: Ensure both price and redemption values are positive

#NUM! Error - Invalid Basis

Cause: Basis argument < 0 or > 4

Solution: Use basis values 0, 1, 2, 3, or 4 only

#NUM! Error - Date Order

Cause: Settlement date ≥ maturity date

Solution: Ensure settlement date is before maturity date

Notes

Always use DATE() function for settlement and maturity dates
Price (pr) represents clean price per $100 face value
Redemption typically equals 100 for par redemption
Default basis=0 uses US (NASD) 30/360 convention
Excel truncates dates and basis to integers

Compatibility

Available in: Excel 2007, Excel 2010, Excel 2013, Excel 2016, Excel 2019, Excel 2021, Microsoft 365

Not available in: Excel 2003 and earlier

Content last reviewed: December 9, 2025
Update frequency: As needed
Excel versions tested: Excel 2007+