The Bank of England notes in a new article:
Broad money is a measure of the total amount of money held by households and companies in the economy. Broad money is made up of bank deposits — which are essentially IOUs from commercial banks to households and companies — and currency — mostly IOUs from the central bank. Of the two types of broad money, bank deposits make up the vast majority — 97% of the amount currently in circulation. And in the modern economy, those bank deposits are mostly created by commercial banks themselves.
Commercial banks create money, in the form of bank deposits, by making new loans. When a bank makes a loan, for example to someone taking out a mortgage to buy a house, it does not typically do so by giving them thousands of pounds worth of banknotes. Instead, it credits their bank account with a bank deposit of the size of the mortgage. At that moment, new money is created. For this reason, some economists have referred to bank deposits as ‘fountain pen money’, created at the stroke of bankers’ pens when they approve loans.
This process is illustrated in Figure 1, which shows how new lending affects the balance sheets of different sectors of the economy (similar balance sheet diagrams are introduced in ‘Money in the modern economy: an introduction’). As shown in the third row of Figure 1, the new deposits increase the assets of the consumer (here taken to represent households and companies) — the extra red bars — and the new loan increases their liabilities — the extra white bars. New broad money has been created. Similarly, both sides of the commercial banking sector’s balance sheet increase as new money and loans are created.
Reserves are, in normal times, supplied ‘on demand’ by the Bank of England to commercial banks in exchange for other assets on their balance sheets. In no way does the aggregate quantity of reserves directly constrain the amount of bank lending or deposit creation.
This description of money creation contrasts with the notion that banks can only lend out pre-existing money, outlined in the previous section. Bank deposits are simply a record of how much the bank itself owes its customers. So they are a liability of the bank, not an asset that could be lent out. A related misconception is that banks can lend out their reserves. Reserves can only be lent between banks, since consumers do not have access to reserves accounts at the Bank of England.