Latest / Monetary Policy Explained with Fexingo: Central Banks, Money Supply, and Interest Rates / How Central Banks Use Reserve Requirements as a Policy Tool
Transcript
- Lucas: If you've ever taken an intro economics class, you've probably seen the money multiplier formula. But here's the thing — that textbook model has been quietly broken for years, and central banks have learned to live without it. I'm talking about reserve requirements. Luna: Reserve requirements — the fraction of deposits banks must hold as cash or at the central bank. They feel like a relic, don't they? The Fed set theirs to 0% in 2020, and other central banks have followed. Lucas: Exactly. But not everyone. The People's Bank of China still uses reserve requirement ratio cuts as a major liquidity tool. And even where the requirement is zero, the concept still influences how we think about money creation. So let's unpack what reserve requirements actually do, and why some central banks have abandoned them while others lean on them heavily. Luna: Start with the basics. If the required reserve ratio is 10%, banks can lend out 90% of a deposit. That loan becomes a new deposit somewhere else, which can be lent out again. That's the multiplier. Lucas: Right. In theory, a $100 million deposit generates up to $1 billion in money supply if the ratio is 10%. But that assumes banks lend out every excess dollar and the new deposits stay in the banking system. In practice, since 2008, many banks hold far more reserves than required — especially in the U.S. and euro area. Luna: So the multiplier is essentially dead in those economies. That's one reason the Fed moved to a floor system for interest rates — they use interest on reserves to set the policy rate, not the quantity of reserves. Lucas: But the story is different in emerging markets. China, for instance, has used RRR cuts as a way to signal easing and free up lending capacity. As of early 2026, the PBOC's reserve requirement ratio for large banks is around 9.5 percent, down from 20 percent a decade ago. Each 50-basis-point cut releases roughly 600 billion yuan into the banking system. Luna: That's about 83 billion dollars. Not exactly pocket change. And it's a direct injection — no bond buying, no forward guidance, just a regulatory change. Lucas: And unlike open market operations, an RRR cut affects all banks proportionally. Small banks get the same proportional boost as big ones. That's one reason it's still popular in economies where the banking sector is more fragmented. Luna: But there's a downside. High reserve requirements act like a tax on banks. If they have to hold 10% at zero or low interest, that's 10% of their deposit base they can't lend. That can push lending outside the regulated system — into shadow banking. Lucas: That's exactly what happened in China in the 2010s. High reserve requirements, combined with interest rate caps on deposits, drove savers and borrowers into wealth management products and trust loans — the shadow banking sector. The PBOC had to balance its RRR policy with the need to keep credit flowing through regulated channels. Luna: So reserve requirements are a blunt tool. But they're also transparent. Everyone can see the ratio. There's no ambiguity about what the central bank has done. Lucas: That transparency is part of why some central banks have kept them. But the bigger reason is that in many economies, the banking system doesn't have a huge pool of excess reserves. The money multiplier still works, roughly. So changing the ratio has a real impact on lending capacity. Luna: Let me ask you this — if reserve requirements are so powerful in some places, why did the Fed and ECB basically abandon them? Was it just because of excess reserves? Lucas: It's partly that. After quantitative easing, banks had trillions in excess reserves. A 10% requirement would have been meaningless because banks already held way more. But there's also a philosophical shift. In a floor system, the central bank controls short-term rates by setting the interest rate on reserves. Reserve requirements become redundant — they don't help set the policy rate. Luna: And they impose a cost on banks for no policy benefit. So the Fed eliminated them. The ECB and Bank of Japan still have very low positive requirements — 1% in the euro area — but they're more like a residual than an active tool. Lucas: Right. But in the U.S., even without a requirement, the concept still matters for understanding how banks create money. And for students of monetary policy, the reserve requirement era shaped how we think about central bank balance sheets and the money supply. Luna: That's a good point. Even if the tool is dormant, the logic behind it — the idea that banks need some anchor for their lending — still influences regulation. Things like the liquidity coverage ratio and the net stable funding ratio are essentially modern reserve requirements. Lucas: Exactly. The LCR requires banks to hold enough high-quality liquid assets to cover 30 days of net cash outflows. That's a reserve requirement, just broader. It's not just cash and central bank reserves, but government bonds too. So the concept lives on in a more sophisticated form. Luna: So if a listener wants to understand monetary policy today, should they still learn the money multiplier? Or is it a waste of time? Lucas: I'd say it's still worth knowing — as a baseline. Because when you encounter a situation where reserve requirements are active, like in China or India, the multiplier logic helps you estimate the impact. And even in a zero-requirement world, it explains why central banks worry about the velocity of money and bank lending appetite. Luna: Let's talk about a concrete example. In February 2026, the PBOC cut the RRR by 50 basis points. How does that play out in practice? Lucas: Say a Chinese bank has 100 billion yuan in deposits. Under a 10% requirement, it must hold 10 billion at the central bank. After a cut to 9.5%, it only needs to hold 9.5 billion. That frees up 500 million yuan that the bank can lend or invest. Across the whole banking system, the total release is around 600 billion yuan, as I mentioned. Luna: And that liquidity flows into the economy — hopefully into productive investment. But it can also fuel asset bubbles if not managed well. Lucas: That's the risk. China's housing market has been fragile, and the PBOC has to be careful not to reignite speculation. So they often pair RRR cuts with macroprudential measures, like tightening loan to value ratios on mortgages. They're using both hands. Luna: Which brings us back to the bigger picture. Reserve requirements are one tool among many. They're not the most precise, but they're powerful. And the fact that some central banks still use them actively shows that old tools don't always become obsolete. Lucas: Absolutely. And you know, talking about old tools that still have value — it reminds me of something. We've been doing this podcast for over 40 episodes now, diving into central bank toolkits. And if that kind of deep dive is useful to you, there's a simple way to support it. Luna: Yeah — if walking through the economy with us has made something click, that's the link. Buy me a coffee dot com slash fexingo. It's not a subscription, just a one-time gesture if the show has been worth a coffee to you. Lucas: And it genuinely helps us keep the podcast ad-free and focused on the substance. So if you've gotten even one insight you've used in a conversation, that's exactly what it's for. Luna: Alright — back to the toolkit. So we've covered reserve requirements as a direct quantitative tool. But there's another way central banks influence lending without setting a ratio: through administered rates like the discount window and the interest rate on excess reserves. Lucas: Right, and that's where we get into the corridor system. In a corridor system, the central bank sets a floor and a ceiling for short-term rates. The floor is the interest rate on reserves — banks won't lend below that because they can park money at the central bank. The ceiling is the discount rate — banks won't borrow above that because they can go to the central bank. Luna: And reserve requirements interact with that corridor. In a system with positive requirements, the demand for reserves is inelastic — banks need to hold a certain amount. That gives the central bank more control over the market rate. But with zero requirements and abundant reserves, the demand curve is flat, and the central bank relies on its administered rates. Lucas: Exactly. So the reserve requirement isn't just about the multiplier — it's also about the plumbing of the money market. When requirements are high, the money market is tighter; when they're zero, it's looser. That has implications for how the central bank implements its policy rate. Luna: And that's a nuance most people miss. It's not just about lending capacity; it's about the operational framework for interest rate control. Lucas: Right. And as we've seen, different central banks have chosen different frameworks. The Fed and the ECB have embraced abundance. The PBOC and the Reserve Bank of India still operate in a world of scarcity. Neither is wrong — they reflect the structure of their banking systems. Luna: So if I had to sum up reserve requirements in one takeaway: they are a powerful tool in economies where banking is traditional and reserves are scarce, but they lose their sting when banks swim in excess liquidity. And even when dormant, the concept is baked into modern prudential rules. Lucas: That's a solid take. And I'd add one more thing: the debate over reserve requirements isn't just about economics, it's about the role of regulation. Do you constrain banks with rules or with prices? Reserve requirements are a rule. Interest on reserves is a price. The shift from rules to prices is one of the big stories of post-crisis monetary policy. Luna: And maybe that's the real lesson — not that one is better, but that the choice depends on context. So next time you see a headline about a central bank cutting reserve requirements, you'll know what it actually means. Lucas: Exactly. Thanks for sticking with us. That's it for this episode of Monetary Policy Explained with Fexingo.