Deposits, reserves, and money creation

The standard mental model of banking goes like this: depositors hand the bank their savings; the bank holds the money in a vault; when a borrower needs a loan, the bank takes the depositors' money out of the vault and lends it to the borrower; the borrower repays with interest; the bank gives some of the interest back to the depositors and keeps the rest. This story is intuitive, widely taught, and not how the system works.

The accurate version is closer to this: when you deposit money in a bank, the bank records a liability — a promise to pay you that amount on demand — and a matching asset (whatever it received, typically a credit to its account at the Federal Reserve or another bank). When the bank makes a loan, it creates a new deposit in the borrower's account by typing a number into a ledger; the loan is the bank's asset, and the new deposit is the bank's liability. No prior depositor's funds were "lent out." The deposit was created by the act of lending.

Understanding this distinction matters because it is the foundation under everything else: deposit insurance (you need it because the deposit is just a promise), reserve requirements (they are a constraint on a process that has already happened), the Federal Reserve's role (it controls the price of the bank's funding, not the quantity of money), and the question of what your money actually is when it sits in a checking account.

A deposit is a bank liability

When you deposit $1,000 in cash at your bank's teller window, the following happens. The bank physically receives the cash (an asset). It increases your deposit balance by $1,000 (a liability). The bank's balance sheet has grown on both sides by $1,000. Later, the bank may take that cash to its Federal Reserve Bank, where it will be converted into reserve balances; the bank's asset shifts from currency to a credit at the Fed, but the deposit liability is unchanged.

The fact that the deposit is a liability of the bank, not an item the bank is custodying for you, has several consequences. First, the bank can use the deposit's economic presence on its balance sheet to fund loans and securities holdings without "taking your money" in any literal sense; your right to demand the deposit is preserved, but the bank's holdings of corresponding assets need not be cash. Second, if the bank fails, your deposit is an unsecured general claim against the bank, ranking with other depositors — which is why federal deposit insurance exists. Third, the legal substance of "your money" in a checking account is a credit balance owed to you by a private corporation; the only money on a U.S. retail bank's balance sheet that is unconditionally money is the cash in the vault and the reserves at the Fed.

This is not an exotic claim. It is the standard accounting treatment of deposits, taught in every banking course, codified in the call reports every bank files, and confirmed in working papers by both the Federal Reserve and the Bank of England — see, for example, the Bank of England's 2014 quarterly bulletin "Money creation in the modern economy," which is the clearest plain-language treatment in print.

Loans create deposits

When a bank originates a loan, it does not move money from a depositor's account to the borrower's account. It executes two journal entries. The borrower's deposit account is credited with the loan amount (a new liability of the bank); the bank records a loan receivable from the borrower (a new asset). The bank's balance sheet has grown on both sides. No prior depositor lost access to anything; no cash moved; the bank simply expanded.

If the borrower then spends the loan proceeds — say, by writing a check to a contractor whose account is at a different bank — the originating bank's deposit liability shrinks (the borrower's account is debited) and its reserve balance at the Fed shrinks by the same amount (to settle the payment to the contractor's bank). The contractor's bank, in turn, gains a deposit liability (the credit to the contractor's account) and a reserve balance (the settlement received). The total stock of bank deposits in the system has not changed merely because the borrower spent the loan; it changed when the loan was originated.

This is the precise sense in which banks "create money." When a bank originates a loan, the broad money supply (M1, M2) increases by the amount of the loan. When a borrower repays principal, the broad money supply decreases by that amount. The Federal Reserve does not create most of the money in circulation; commercial banks do, through their lending decisions. The Fed influences the process by setting the price of bank reserves, but the quantity of bank-created money is determined by the lending behavior of thousands of independent institutions, subject to capital, liquidity, and credit-quality constraints.

What reserves are, and aren't

Bank reserves are the deposit balances that depository institutions hold at their Federal Reserve Bank. They are central-bank money — a direct liability of the Federal Reserve — and they are used to settle payments between banks. When your check clears, the paying bank's reserve account is debited and the receiving bank's reserve account is credited; the actual settlement is reserve-to-reserve, even though to you it looks like deposit-to-deposit.

Reserves serve two purposes. First, they let banks settle interbank payments without writing checks to each other or shipping cash. Second, they form the operational floor of the monetary-policy regime: by paying interest on reserve balances (IORB), the Federal Reserve sets a floor under short-term interest rates, because no bank will lend overnight at a rate below what it can earn on reserves at the Fed. See the Federal Reserve, plainly for the policy plumbing.

What reserves are not is a per-deposit reserve account on your behalf. There is no specific reserve corresponding to your deposit; the reserves are aggregate and fungible. And reserves are not a constraint on lending in the present U.S. regime, for two reasons. First, the U.S. has operated in an "ample reserves" framework since 2008, in which the total quantity of reserves is far in excess of what banks need to settle payments. Second, in March 2020 the Federal Reserve set the reserve requirement ratio under Regulation D to zero percent. Banks today are not required to hold any minimum reserve against their deposit liabilities; they choose to hold reserves for liquidity and for the interest they earn on them.

The same 2020 change suspended the historical Reg D limit of six "convenient transfers" per month from a savings account, which had been the regulatory basis for the long-standing inconvenience of savings-account use. See savings accounts.

Bank money versus central-bank money

The system contains two kinds of money. Central-bank money is money issued by the Federal Reserve: Federal Reserve notes (the green cash) and reserve balances held by banks at the Fed. Central-bank money is the only money the Fed creates; it is a direct liability of the Fed, with no credit risk. Bank money is the deposit balances issued by commercial banks. Bank money is created when banks lend; it is a liability of the issuing commercial bank, with credit risk that is mitigated for most retail depositors by FDIC insurance up to the standard maximum of $250,000 per depositor, per insured bank, per ownership category.

For an ordinary depositor, the two kinds of money are nearly indistinguishable in daily use. You can convert bank money to central-bank money by withdrawing cash from an ATM; you can convert central-bank money to bank money by depositing the cash. The conversion is one-to-one and immediate (within ATM limits), provided your bank is solvent. The distinction matters in two situations: when the bank is failing (your bank-money deposit becomes an insurance claim, while cash in your wallet remains good), and when you think about who is bearing the residual credit risk on every "dollar" you hold electronically.

What constrains a bank's expansion

If reserves do not constrain lending, what does? Three things.

First, capital requirements. A bank's loans are funded partly by deposits and partly by equity capital. Regulators require that banks maintain capital above defined thresholds relative to risk-weighted assets; growing the loan book requires growing the capital base proportionally, which requires retained earnings or new equity issuance. The capital framework (Basel III as implemented in the U.S.) is the main brake on aggregate bank expansion.

Second, liquidity. Even though new loans create new deposits in aggregate, an individual bank that lends aggressively may find the new deposits leaving immediately for other banks as borrowers spend the proceeds. To settle the resulting net outflows, the lending bank needs reserves or other liquid assets. A bank that loses deposits faster than it can fund itself faces a liquidity problem regardless of whether it is solvent. This is the dynamic that brought down Silicon Valley Bank in March 2023; see 2023: SVB, Signature, First Republic.

Third, credit demand and credit quality. A bank cannot lend more than there are creditworthy borrowers willing to borrow at a price the bank will accept. In a recession, even a well-capitalized bank with abundant liquidity may shrink its loan book because credit demand falls and the borrowers who do want to borrow are not creditworthy.

Why this matters to you

The reason this material belongs in a retail-banking reference, and not just in a textbook on monetary economics, is that it changes how you read the rest of the system. Federal deposit insurance is not a strange add-on; it is the answer to the structural fact that your deposit is an unsecured claim. The CFPB's complaint database is not bureaucratic excess; it is one of the few channels of accountability available against an institution that has issued you a liability and is now disputing the terms. The 2023 bank failures look much less surprising once you internalize that a bank's funding can vanish overnight in a digital era, regardless of how much vault cash the bank has. And the periodic insistence that "the bank is just holding your money" — heard often in marketing and occasionally in legislative debate — is a statement of how banks present themselves, not a description of what they are.

Limits and uncertainty

This page is a deliberately simplified treatment of a deep technical literature. It glosses many real-world complications: the role of money market funds and the ON RRP facility in the broader money supply; the distinction between M1 and M2 and which deposits count where; the special status of reciprocal-deposit and brokered-deposit arrangements; the central-bank digital currency question (which the Federal Reserve has explored but not adopted); the differences in money creation between the U.S. and other monetary systems. Readers who want to go deeper should start with the Bank of England's "Money creation in the modern economy" paper and the Federal Reserve's "Money Stock and Reserves" technical material. The core claims here — that deposits are bank liabilities, that loans create deposits, and that the reserve requirement is currently zero — are not contested.