The Price of Government Debt
Unlike standard corporate bonds, United States Treasury Bills (T-Bills) do not pay you regular, monthly interest payments. Instead, the government uses a “Zero-Coupon” system. The government promises to pay you exactly $10,000 (the face value) six months from now. To guarantee your profit, the government simply sells you that $10,000 promissory note today at a massive discount.
If you buy the note today for $9,750, and the government gives you $10,000 in six months, you have guaranteed a flat $250 profit. The problem is that the global financial markets fluctuate every single millisecond. The government does not set the price; the market sets the discount yield. If the market dictates that the current yield for a 6-month T-Bill should be 4.85%, how do you mathematically calculate exactly how much money you need to hand the government today to achieve that specific yield?
To instantly translate a quoted market yield percentage into the exact, physical purchase price of the bond, you must use the TBILLPRICE (Treasury Bill Price) function in Microsoft Excel.
Understanding the Syntax
The TBILLPRICE function is incredibly streamlined because it assumes all the rigid mathematical rules required by the US Government (such as the artificial 360-day calendar year).
=TBILLPRICE(settlement, maturity, discount)
- settlement: The exact date you are physically handing your cash to the government or the secondary market broker to purchase the T-Bill.
- maturity: The exact date the Treasury Bill officially expires and the government deposits the massive face value into your bank account. (Note: By federal law, this date must be exactly one calendar year or less from the settlement date).
- discount: The current market yield percentage quoted by the financial broker.
Example 1: Calculating the Purchase Price
Assume you are a corporate treasurer tasked with safely parking $1,000,000 of excess company cash. You decide to buy a block of US Treasury Bills.
You plan to execute the massive purchase (Settlement) on April 15, 2024. You are buying 90-day T-Bills, which means they will officially mature on July 14, 2024. The current financial market quotes the discount yield for these specific bills at exactly 5.25%.
You know you will receive exactly $1,000,000 on July 14th. But exactly how much cash do you need to wire out of the corporate bank account on April 15th to acquire them?
Let’s map out the variables cleanly in a spreadsheet:
- Cell A1 (Settlement):
=DATE(2024, 4, 15) - Cell A2 (Maturity):
=DATE(2024, 7, 14) - Cell A3 (Discount):
5.25%
To calculate the exact purchase price, click on cell B1 and type:
=TBILLPRICE(A1, A2, A3)
How this works:
- Excel calculates the exact physical number of days between April 15 and July 14 (90 physical days).
- It analyzes the 5.25% required yield against the government’s mandatory 360-day mathematical calendar.
- It calculates the exact monetary discount required over that 90-day period to guarantee the 5.25% return.
- It instantly outputs 98.6875.
Interpreting the Output
Like all professional bond pricing tools in Excel, the number 98.6875 is not a flat dollar amount. It is the price per $100 of face value.
Because you are buying a massive block of T-Bills with a total face value of $1,000,000, you must convert Excel’s output.
- Take the output (98.6875) and divide it by 100. (Result:
0.986875) - Multiply that result by the total face value ($1,000,000).
- The final result is $986,875.
You must wire exactly $986,875 out of the corporate account on April 15th. On July 14th, the government will hand you $1,000,000, generating a guaranteed $13,125 profit that perfectly satisfies the 5.25% market yield. By mastering the TBILLPRICE function, you gain the ability to instantly calculate the massive capital requirements of government debt acquisitions.