Interest on Reserves (IOR)
What Is Interest on Reserves (IOR)?
The rate of interest that the Federal Reserve pays to depository institutions (banks) on the reserve balances they hold at the Fed.
Interest on Reserves (IOR) refers to the interest payments the Federal Reserve makes to eligible banks on the funds they keep on deposit at the Federal Reserve Banks. Before 2008, banks earned zero interest on these reserves, essentially viewing them as a regulatory cost. The Financial Services Regulatory Relief Act of 2006 authorized the Fed to pay interest, and this authority was accelerated to October 2008 during the financial crisis. Today, IOR is a cornerstone of the Fed's "ample reserves" framework. By adjusting the rate it pays on reserves, the Fed can influence the federal funds rate (the rate banks charge each other for overnight loans) without actively managing the supply of reserves every day through open market operations. The term encompasses what was formerly known as Interest on Required Reserves (IORR) and Interest on Excess Reserves (IOER). Since July 2021, these have been unified into a single rate called the Interest on Reserve Balances (IORB) rate.
Key Takeaways
- A primary monetary policy tool used by the Federal Reserve to control short-term interest rates.
- Effectively sets a floor for the federal funds rate.
- Consists of Interest on Reserve Balances (IORB), which replaced the separate IORR and IOER in 2021.
- Encourages banks to hold excess cash at the Fed rather than lending it out at risky or lower rates.
- Allows the Fed to manage the money supply without needing to drastically change the size of its balance sheet.
How Interest on Reserves Works
The mechanism is straightforward: if the Fed pays banks 5% to keep money safe at the Fed, no rational bank would lend that money to another bank or borrower for less than 5% (assuming similar risk). Thus, the IORB rate acts as a "reservation price" or a floor for short-term interest rates. When the Fed wants to raise interest rates to fight inflation, it raises the IORB rate. Banks immediately demand higher rates for lending to consumers and businesses because their opportunity cost (leaving money at the Fed) has gone up. Conversely, if the Fed wants to stimulate the economy, it lowers the IORB rate. This makes sitting on cash less attractive for banks, incentivizing them to lend money out to the real economy to seek better returns.
Evolution: From IOER to IORB
Historically, the Fed focused on **IOER** (Interest on Excess Reserves) because that was the marginal rate that mattered for policy. Required reserves were a fixed constraint, but "excess" reserves were what banks traded in the fed funds market. In 2020, the Fed eliminated reserve requirements (setting them to zero) to support liquidity during the pandemic. This made the distinction between "required" and "excess" reserves moot. Consequently, in 2021, the Fed simplified the terminology to **Interest on Reserve Balances (IORB)**. While traders may still use the term IOER out of habit, IORB is the current official policy rate.
Important Considerations
The IORB rate is usually set slightly higher than the effective federal funds rate (EFFR). This is because not all institutions that lend in the fed funds market (like Federal Home Loan Banks) are eligible to earn interest on reserves. These institutions are willing to lend at rates slightly below the IORB, and banks arbitrage this by borrowing from them and depositing at the Fed to earn the spread. This arbitrage activity keeps the fed funds rate within the Fed's target range. Understanding IOR is essential for fixed-income traders, as it is the primary lever moving the short end of the yield curve.
Real-World Example: Raising Rates
Scenario: The economy is overheating, and inflation is 6%. The Fed decides to raise the target fed funds range from 2.0% to 2.5%. To implement this, the Fed raises the Interest on Reserve Balances (IORB) rate from 2.15% to 2.65%. 1. **Bank A** has $1 billion in cash. It can now earn 2.65% risk-free by leaving it at the Fed. 2. **Bank B** asks to borrow money overnight from Bank A. 3. Bank A refuses to lend at the old rate of 2.0% because it can get 2.65% at the Fed. 4. Bank A demands at least 2.65% (plus a spread for risk) to lend to Bank B. 5. The market interest rate snaps up to the new level almost instantly.
Common Beginner Mistakes
Clarifying common confusion points:
- Confusing IOR with the Fed Funds Rate. IOR is what the Fed pays banks; the Fed Funds Rate is what banks pay each other. They are linked but distinct.
- Thinking IOR is a subsidy for banks. While it pays banks, its primary purpose is policy implementation (controlling rates), not bank profitability.
- Believing reserve requirements still exist. The Fed set reserve requirements to zero in March 2020, making all reserves essentially "excess" (now just "balances").
FAQs
The Fed pays interest using earnings from its portfolio of assets (primarily Treasury bonds and Mortgage-Backed Securities). Historically, the Fed earns much more on its assets than it pays in interest to banks, remitting the profit to the US Treasury. However, if short-term rates (IORB) rise above the yield on the Fed's long-term bond holdings, the Fed can experience an operating loss.
IOR drives the Prime Rate and other consumer interest rates. When the Fed raises the IOR, interest rates on credit cards, car loans, and adjustable-rate mortgages go up, making borrowing more expensive for households.
IOR is the rate banks *earn* on deposits at the Fed. The Discount Rate (Primary Credit Rate) is the rate banks *pay* to borrow directly from the Fed at the "Discount Window." The Discount Rate is set higher than the IOR to discourage banks from relying on the Fed for funding.
Theoretically, yes. This would mean charging banks to hold deposits, effectively a negative IOR. While other central banks (ECB, BOJ) have used negative rates, the US Fed has historically been reluctant to use negative rates due to concerns about money market fund stability and legal authority.
The Bottom Line
Interest on Reserves (IOR/IORB) is the modern steering wheel of US monetary policy. By setting the rate it pays banks to hold cash, the Federal Reserve exerts precise control over short-term interest rates throughout the economy. For investors, monitoring changes in the IORB is identical to monitoring the Fed's rate hike/cut decisions. It represents the risk-free opportunity cost of capital for the banking system, influencing everything from savings account yields to corporate bond rates.
Related Terms
More in Monetary Policy
At a Glance
Key Takeaways
- A primary monetary policy tool used by the Federal Reserve to control short-term interest rates.
- Effectively sets a floor for the federal funds rate.
- Consists of Interest on Reserve Balances (IORB), which replaced the separate IORR and IOER in 2021.
- Encourages banks to hold excess cash at the Fed rather than lending it out at risky or lower rates.