This lesson introduces the foundational concept of the time value of money and the mechanics of interest rate calculations, which underpin all treasury and corporate finance activities .

1.1 The Core Principle of the Time Value of Money
The time value of money (TVM) is the principle that a sum of money today is worth more than the same sum in the future due to its potential earning capacity. This is the most fundamental concept in finance and is critical for valuation, investment analysis, and financial planning . The ACT Certificate in Treasury Fundamentals specifically includes “An introduction to interest rates and related calculations” as a core requirement, highlighting its essential nature .

1.2 Key Terminology and Calculations
Understanding key terms is the first step to effective application:

• Simple Interest: Calculated on the original principal only. The formula is: Interest = Principal × Rate × Time. This method is commonly used for short-term instruments like money market deposits .

• Compound Interest: Calculated on the principal and the accumulated interest of previous periods. The concept of “interest on interest” is key for understanding the growth of investments and the cost of borrowing. The ACT syllabus specifically covers the “frequency of compounding” as a key consideration .

• Nominal vs. Effective Interest Rates:

  • The Nominal Interest Rate (or Annual Percentage Rate – APR) is the stated rate without accounting for compounding.

  • The Effective Annual Rate (EAR) is the actual annual rate earned (or paid) when compounding is taken into account. A key calculation is converting between “annual and semi-annual compounding frequencies” and calculating the “effective annual rate” .

• Day Count Conventions: Different financial instruments use different conventions to calculate the fraction of a year for interest calculations (e.g., 30/360, Actual/360, Actual/365). The syllabus requires candidates to “calculate simple interest using different day count and annual basis conventions” .

1.3 Discounting and Compounding
These are the two core operations of TVM.

• Compounding: Determining the future value of a present sum.

• Discounting: Determining the present value of a future sum. This is the reverse of compounding and is the foundation of project appraisal and bond valuation. The ACT syllabus requires the ability to “calculate present value and future value using the techniques of discounting and compounding” . This involves identifying “determinants of interest rates,” with the time value of money being a primary component .