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Business Economics · Role, structure and stability of the financial system

How Banks Create Money and the Central Bank's Role

Updated 11 October 2026 · Fact-checked

Banks take deposits and lend most of them out. Each loan becomes a new deposit elsewhere, so total deposits grow. With a reserve ratio r, the maximum multiplier is 1 ÷ r. The central bank sets policy rates, controls reserves and acts as lender of last resort to protect stability.

Understand Banking, Money Creation and Central Bank Role

A bank takes deposits from savers and lends to borrowers. It earns the gap between the interest it charges and the interest it pays. Deposits are the bank's liabilities. Loans and reserves are its assets.

Banks keep only a fraction of deposits as reserves: cash and balances with the central bank. This is fractional reserve banking. The reserve fraction may be set by regulation or chosen by the bank for safety. The rest can be lent.

Money creation works like this. You deposit ₹1,000. The bank keeps part as reserves and lends the rest. The borrower spends it, and the seller deposits it in a bank. That bank lends part again. Each round adds new deposits. The total is a geometric series, so the total increase in deposits is the initial deposit × 1 ÷ r, where r is the reserve ratio. This is the money multiplier. It is a maximum. It assumes banks lend every spare rupee and that borrowers redeposit all the money in banks.

In practice, leakages cut the multiplier. People hold cash. Banks hold excess reserves. Weak loan demand also limits lending. If a fraction c of money is held as cash, the multiplier becomes smaller than 1 ÷ r.

The central bank (the RBI in India) has several roles. It is the monetary authority: it sets the policy rate, runs open market operations and can change reserve requirements. It is banker to banks and to the government. It supervises banks. It is also lender of last resort: it lends to solvent banks facing a liquidity shortage, usually against good collateral and at a penalty rate, so a run on one bank does not spread. The aim is financial stability. A risk is moral hazard: banks may take more risk if they expect rescue.

Key rules to remember

Simple money multiplier
m = 1 ÷ r
r is the reserve ratio as a decimal. This is the maximum multiplier, assuming no cash leakage and no excess reserves.
Maximum total deposit creation
Total new deposits = initial deposit ÷ r
The initial deposit is included in the total. Lending created = total deposits − initial deposit.
Multiplier with cash leakage
m = (1 + c) ÷ (r + c)
c is the cash-to-deposit ratio and r the reserve-to-deposit ratio. This applies to the money supply multiplier on the monetary base. State the assumption used.
Geometric series for rounds of lending
Total = D × (1 + (1 − r) + (1 − r)² + ...) = D ÷ r
Valid for 0 < r ≤ 1, so the series converges.
Bank balance sheet identity
Assets = Liabilities + Capital
Reserves and loans are assets. Deposits are liabilities.

How to solve Banking, Money Creation and Central Bank Role questions

Use this method for numerical and descriptive questions on bank money creation and central bank functions.

  1. 1Read the question and identify what is asked: new deposits, new loans, the multiplier, or the central bank's role.
  2. 2Write down the reserve ratio r as a decimal. Note whether any cash leakage or excess reserves are given.
  3. 3Choose the formula. Use 1 ÷ r if there are no leakages. Use (1 + c) ÷ (r + c) if a cash ratio is given and the question is about the money supply.
  4. 4Calculate the result. Check whether the question wants total deposits, or only new lending (total minus the initial deposit).
  5. 5Check the size. The answer should be larger than the initial amount and should not exceed the simple multiplier result.
  6. 6For descriptive parts, name the central bank tool or role, explain how it works, and state the effect on liquidity, credit and stability.
  7. 7State assumptions and one limitation, such as leakages or moral hazard.

Quickest way: Reserve ratio shortcut

When to use it: Use this for multiple-choice questions on deposit creation with a given reserve ratio.

  1. Convert r to a fraction, for example 10% = 1/10.
  2. Invert it to get the multiplier: 1/10 gives 10.
  3. Multiply by the initial deposit for total deposits.
  4. Subtract the initial deposit if asked for new loans.
  5. If leakages are mentioned, say the answer is below the simple maximum and rule out options above it.

Common mistakes in Banking, Money Creation and Central Bank Role

  • Using the multiplier as the exact increase in money supply.

    The formula looks like a fixed rule.

    Fix: Call 1 ÷ r the maximum. Real creation is lower because of cash holding and excess reserves.

  • Entering r as a percentage, such as 1 ÷ 10 instead of 1 ÷ 0.10.

    Students forget to convert 10% to a decimal.

    Fix: Always write r as a decimal or fraction before inverting.

  • Confusing total deposits with new lending.

    The initial deposit is part of the total but is not a new loan.

    Fix: Lending created = total deposits − initial deposit. Read the question wording.

  • Saying banks lend out only money that depositors already saved.

    A simple 'intermediary' view of banks is taught first.

    Fix: Explain that loans create matching deposits, so the banking system expands money, within reserve and capital limits.

  • Describing lender of last resort as bailing out any failing bank.

    News stories blur liquidity support and solvency rescue.

    Fix: Say it supports solvent but illiquid banks, against collateral, usually at a penalty rate. Mention moral hazard.

  • Mixing up the central bank's tools with its roles.

    Both appear in the same list.

    Fix: Roles: monetary authority, banker to banks, regulator, lender of last resort. Tools: policy rate, open market operations, reserve requirements.

Worked examples

Example 1

The reserve ratio is 8% and there are no cash leakages. A customer deposits ₹2,00,000 in a bank. Find the maximum total increase in deposits and the maximum new lending in the banking system.

Show the solution
  1. r = 0.08, so the multiplier = 1 ÷ 0.08 = 12.5.
  2. Total deposits = ₹2,00,000 × 12.5 = ₹25,00,000.
  3. New lending = total deposits − initial deposit = ₹25,00,000 − ₹2,00,000 = ₹23,00,000.
  4. Check: reserves held = 8% × ₹25,00,000 = ₹2,00,000, which equals the initial deposit. This is consistent.

Answer: Maximum total deposits are ₹25,00,000 and maximum new lending is ₹23,00,000.

Example 2

Explain why the money multiplier in practice is lower than 1 ÷ r, and describe how the central bank acts as lender of last resort during a bank run.

Show the solution
  1. State the simple result: with reserve ratio r, the maximum multiplier is 1 ÷ r. It assumes banks lend all spare reserves and all money is redeposited.
  2. Give the leakages: people hold some money as cash, so less is redeposited. Banks may hold excess reserves because loan demand is weak or they fear losses. Each leakage reduces later rounds of lending.
  3. Describe a run: depositors fear losses and withdraw at once. A bank holds only a fraction of deposits in reserves and its loans cannot be sold quickly, so it may be unable to pay even if it is solvent.
  4. Describe the central bank action: it lends to the solvent bank, against good collateral and usually at a penalty rate, to meet withdrawals. This restores confidence and stops contagion to other banks.
  5. State the limitation: if banks expect rescue, they may take more risk (moral hazard). So the central bank also supervises banks and limits support to liquidity, not insolvency.

Answer: The multiplier is below 1 ÷ r because of cash holding and excess reserves. The lender of last resort lends to solvent but illiquid banks against collateral, which stops runs spreading. The cost is moral hazard, managed through supervision.

Exam tips

  • Show the formula, the decimal value of r and the working. Method marks are given in written questions.
  • Read whether the question asks for total deposits or new loans. Many students lose marks here.
  • For descriptive questions, link each central bank role to stability: liquidity, confidence, and limiting contagion.
  • In multiple-choice questions, remove any option that exceeds the simple multiplier result when leakages are present.
  • Always state the assumptions: no cash leakage, banks fully lent, all money redeposited.

Practice questions from Role, structure and stability of the financial system

Banking, Money Creation and Central Bank Role in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Banking, Money Creation and Central Bank Role: frequently asked questions

How do banks create money?

When a bank makes a loan, it credits the borrower's account with a new deposit. That deposit is money. When the borrower spends it, the receiving bank gets a deposit and can lend again. Reserve rules and capital limits cap the expansion.

What is the money multiplier formula?

The simple money multiplier is 1 ÷ r, where r is the reserve ratio as a decimal. It is the maximum. If people hold cash, a form such as (1 + c) ÷ (r + c) applies to the money supply, where c is the cash-to-deposit ratio.

What does lender of last resort mean?

It means the central bank lends to banks that cannot raise funds elsewhere, usually against collateral. It is meant for solvent banks facing a liquidity shortage. It helps prevent a run on one bank from becoming a wider crisis.

What is the RBI's role in the Indian financial system?

The RBI is India's central bank. It sets monetary policy, regulates and supervises banks, manages liquidity and acts as banker to banks and the government. It also acts as lender of last resort to protect financial stability.