Plain definition
The time value of money recognises that a riyal available today is different from a riyal received later. Cash held today can be used, invested, or kept available for an obligation. Future cash also carries timing, inflation, and collection risk. For that reason, investment decisions compare dated cash flows rather than simply adding their nominal amounts.
Discounting moves a future cash flow back to a value today. Compounding moves today’s cash forward to a future amount. Both calculations require a stated rate and a clear period. The rate must match the cash-flow basis: nominal cash flows need a nominal rate, and real cash flows need a real rate.
Illustrative example
Monetary examples use Saudi riyals (SAR). The same principles apply in other currencies.
Suppose a supplier offers a company either today or in one year. If the company can earn 10% on cash of comparable risk, the two amounts are equal on that basis because grows to in a year.
That does not mean the later payment is automatically acceptable. The company may need cash today for payroll, or the collection risk may be higher than the assumed rate captures. The calculation makes the comparison possible; management still decides whether the risk and timing fit the business.
A stated rate without a stated timing convention is not enough. Monthly, annual, nominal, and real rates cannot be mixed casually.
Why it matters
Ignoring time value makes delayed cash look as useful as cash available for today’s commitments. That can make a long project or slow-paying contract appear stronger than it is, especially when the business has limited liquidity.
Practical consequence
Put every cash flow on a timeline. State whether each amount occurs at the beginning, end, or through a period, and document the rate, compounding frequency, currency, and risk basis. Use the same conventions in the forecast and the discounting. If the conclusion changes with a modest rate or timing change, treat that sensitivity as a decision issue rather than hiding it in one headline number.