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DISC Function (LibreOffice Calc)

Financial Intermediate LibreOffice Calc Introduction not established

The DISC function returns the discount rate of a security given its price, settlement date, maturity date, and redemption value. It is essential for valuing Treasury bills, commercial paper, and other discount securities.

Verification status: Consult the documentation, examples and any stated test scope below. How formula examples are checked

Availability and version history

  • Introduced: Documented by LibreOffice 26.8.1.1; original introduction not established.
  • Availability: Supported in LibreOffice 26.8.1.1, verified against its function registry. This identifies a supported release, not a final working version.
  • Scope: Desktop Calc, using the English function name. Availability in other spreadsheet applications is separate.
  • Checked: 2026-10-14 — function reference; versioned support. Documentation/source check; not a new native test. Existing example-specific test claims below retain their stated scope.
The **DISC** function calculates the **annual discount rate** of a discount security based on its price. It is the inverse of PRICEDISC and is essential for valuing Treasury bills, commercial paper, and other zero‑coupon discount instruments.

What the DISC Function Does

  • Computes the discount rate of a discount (zero‑coupon) security
  • Uses settlement date, maturity date, price, and redemption value
  • Supports multiple day‑count basis systems
  • Works with real dates, serial numbers, and DATEVALUE
  • Fully compatible with Excel’s DISC function

It is designed to be precise, finance‑grade, and ideal for money‑market analytics.

Syntax

DISC(settlement; maturity; price; redemption; [basis])

Arguments

  • settlement:
    The date the security is traded to the buyer.

  • maturity:
    The date the security matures.

  • price:
    Price per 100 face value.

  • redemption:
    Redemption value per 100 face value (usually 100).

  • basis (optional):
    Day-count convention:

basis Day-count convention
0 US 30/360
1 Actual/Actual
2 Actual/360
3 Actual/365
4 European 30/360

Basic Examples

Discount rate of a Treasury bill

=DISC("2024-03-15"; "2024-09-15"; 97.8; 100; 2)

Using Actual/Actual

=DISC(A1; A2; Price; 100; 1)

Using text dates

=DISC(DATEVALUE(A1); DATEVALUE(A2); Price; Redemption)

Advanced Examples

Commercial paper discount rate

=DISC("2024-01-10"; "2024-04-10"; 98.6; 100; 2)

From imported CSV timestamps

=DISC(DATEVALUE(LEFT(A1;10)); DATEVALUE(LEFT(A2;10)); Price; Redemption)

From Excel serial dates stored as text

=DISC(DATE(1899;12;30)+VALUE(A1); DATE(1899;12;30)+VALUE(A2); Price; Redemption)

Compute price from discount rate (inverse)

=PRICEDISC(Settlement; Maturity; Discount; Redemption; Basis)

Compute money‑market yield

=Discount * (360 / Days)

Compute effective annual yield

=(Redemption / Price) - 1

Edge Cases and Behavior Details

DISC returns a numeric value (annual discount rate)

Accepts:

  • Real dates
  • Serial numbers
  • DATEVALUE outputs

Invalid text → Err:502

Behavior details

  • Settlement < Maturity must hold
  • Basis must be 0–4
  • Price must be > 0
  • Time components ignored
  • Uses clean price (no accrued interest)

DISC of an error → error propagates

Common Errors and Fixes

Err:502 — Invalid argument

Cause:

  • Dates not recognized
  • Basis outside 0–4
  • Price not numeric

Fix:

  • Wrap dates with DATEVALUE
  • Validate basis
  • Ensure price is numeric

Err:504 — Invalid date sequence

Cause:

  • Settlement after maturity

Fix:

  • Correct date order

Unexpected discount rate

Cause:

  • Wrong basis
  • Incorrect price
  • Incorrect redemption value

Fix:

  • Verify inputs carefully
  • Confirm day-count convention

Best Practices

  • Use Actual/360 (basis 2) for money‑market instruments
  • Use Actual/365 (basis 3) for UK T‑bills
  • Normalize text dates with DATEVALUE
  • Validate price carefully
  • Use DISC with PRICEDISC and YIELDDISC for full discount‑security modeling
DISC is your discount‑rate engine — essential for T‑bills, commercial paper, and any professional money‑market model.
  • Use PRICEDISC to compute price from discount rate
  • Use YIELDDISC to compute yield from price
  • Use PRICEMAT for interest‑at‑maturity securities
  • Use ACCRINTM for zero‑coupon bonds
  • Use YEARFRAC for fractional year calculations

By mastering DISC and its companion functions, you can build powerful, accurate, and fully professional money‑market valuation models in LibreOffice Calc.