Reserves have several meanings. They can be liquid funds kept available, accounting amounts, bank balances at a central bank, official reserve assets or estimates of future insurance obligations. In energy, reserves refer to recoverable resources.
The context matters. A figure described as a reserve does not necessarily represent cash in a separate account.
Cash and accounting reserves
A cash reserve is money a person or organisation keeps available for payments, interruptions to income or unexpected costs. For example, a business might retain cash to cover wages while waiting for customers to pay.
Accounting reserves can be components of shareholders’ equity, the residual interest in assets after liabilities are deducted. Examples include revaluation and foreign-currency translation reserves. These record particular accounting changes rather than a separate cash balance. IAS 1 requires a description of the nature and purpose of each reserve within equity.
A company can therefore report substantial equity reserves while holding little cash. The cash-flow statement and balance-sheet notes provide different information from the equity reserve figure.
Bank reserves and reserve requirements
Bank reserves commonly include vault cash and balances held at a central bank. Reserve balances are the bank’s deposits at that central bank, used to make and receive payments. The Federal Reserve explains that these deposits are liabilities on its own balance sheet.
Reserve requirements are rules specifying a minimum amount institutions must hold against particular liabilities. They vary by jurisdiction. The US Federal Reserve reduced its reserve-requirement ratios to zero from 26 March 2020. That does not mean banks stopped holding reserve balances or that other liquidity rules disappeared.
Official reserve assets
Official reserve assets are external assets readily available to, and controlled by, monetary authorities for purposes such as financing international payment needs and intervening in currency markets. Under the IMF’s classification, they can include foreign-currency assets, monetary gold, special drawing rights and a reserve position in the IMF.
Special drawing rights, or SDRs, are international reserve assets created by the IMF. They can be exchanged for usable currencies. Foreign-exchange reserves are a narrower category than total official reserve assets: gold is not foreign exchange.
A reserve currency is a currency held in official reserves. The mix of currencies changes over time; a numerical share needs a stated reporting period and dataset.
Insurance reserves and future payments
Insurance reserves estimate obligations under the relevant accounting and actuarial rules. They are not simply a pot of premiums or a forecast of income. The IFRS Foundation’s explanation of insurance cash flows covers premiums, claims, benefits and expenses, with adjustments for timing and risk.
A simplified example shows how payment dates affect present value, the amount a future payment represents today at an assumed discount rate. Suppose known payments of US$500,000, US$300,000 and US$200,000 fall at the ends of years one, two and three. At a constant annual 6% rate:
- Year one: US$500,000 ÷ 1.06 = US$471,698.11.
- Year two: US$300,000 ÷ 1.06² = US$266,998.93.
- Year three: US$200,000 ÷ 1.06³ = US$167,923.86.
The sum is US$906,620.90. If that amount earns exactly 6% annually, with no fees or tax, it funds the three scheduled withdrawals under these assumptions. It is not a single US$1 million payment on one date, or a complete valuation of an uncertain insurance liability.
Oil and gas reserves
Proved oil and gas reserves are estimated quantities recoverable with reasonable certainty under existing economic and operating conditions, according to the US Energy Information Administration. They differ from all the oil or gas believed to exist underground.
Estimates change with production, discoveries, prices, costs, technology and new information. A large reserve estimate alone does not establish future production, export volumes or market dominance.
Last checked and updated on November 2, 2026 by the MBN editorial team.