What is the interest on reserves policy?

The short answer

Interest on reserve balances is the interest rate the Federal Reserve pays banks for the reserves they keep on deposit at the Fed. The mechanism is simple: a bank that earns 5% risk-free from the Fed will not lend overnight to another bank at less than 5%. IORB therefore sets a floor under the federal funds rate.

This may sound technical, but it represents one of the deepest structural changes in modern monetary policy. Before 2008, the Fed controlled rates by adjusting the quantity of reserves in the system — adding or draining reserves to make them scarcer or more abundant. After 2008, with reserves vastly expanded by QE, scarcity was no longer a useful lever; the Fed switched to controlling the price of reserves through IORB.

The implication is that the Fed can now run a very large balance sheet without losing control of short-term rates. This is why post-QE balance sheets have remained structurally larger than the pre-2008 norm.

→ New to monetary policy? How does the Federal Reserve create money?

What the data shows

The IORB regime has been in effect for more than 17 years and has proven remarkably effective at controlling short-term rates.

The empirical record (Federal Reserve, FRED, 2008-2025):

• The Fed began paying interest on reserves on October 6, 2008, under emergency authority granted by the Emergency Economic Stabilization Act
• From 2008 to 2021, the Fed used two rates: IORR (on required reserves) and IOER (on excess reserves); these were merged into IORB on July 29, 2021
• The effective federal funds rate (EFFR) has tracked within the FOMC target range with high precision since 2008, even with reserves ranging from $1 trillion to over $4 trillion
• The IORB-EFFR spread has averaged approximately 5 basis points since 2021, with brief excursions during March 2020 (COVID stress) and September 2019 (repo crisis)

The exception that nuances the framework: IORB sets a floor only for institutions eligible to earn it (banks). Non-bank money market participants (money market funds, GSEs) trade at lower rates, which is why the Fed added the overnight reverse repo (ON RRP) facility in 2013 as a complementary floor for them.

→ Dataset: Federal funds rate history

Why it happens — the macro mechanism

IORB transforms the conduct of monetary policy through three interlocking channels.

Floor system mechanics. Under the floor system, the Fed sets IORB at the upper bound of its target range, and the federal funds rate naturally settles just below it. Banks earning IORB risk-free have no incentive to lend reserves to other banks at lower rates, so the entire short-term yield curve is anchored from above.

Decoupling channel — the disabled monetary aggregate link. Contrary to the textbook view that monetary policy works by adjusting the quantity of money in circulation, IORB explicitly decouples balance sheet size from policy stance. The Fed can run a $7 trillion balance sheet (post-QT 2025) and still maintain a 5% policy rate, because the rate is set administratively rather than through reserve scarcity. This is why monetary aggregates like M2 lost their predictive power for inflation after 2008 — the transmission channel they relied on no longer operates.

This decoupling is also why the academic monetarist tradition (Friedman, Schwartz) struggles to explain post-2008 monetary policy: the operating system has fundamentally changed.

Term premium and credit channels. By setting a floor on overnight rates, IORB indirectly anchors the entire short end of the yield curve. Bank lending rates, repo rates, and money market yields all adjust around the IORB anchor, transmitting Fed decisions to the real economy through the standard credit channel.

Synthesis by regime: under the pre-2008 corridor system, monetary policy worked by adjusting reserve scarcity and small balance sheet operations had large effects on rates; under the post-2008 floor system, balance sheet size and policy rate are decoupled — the Fed can adjust either independently; under the post-2025 ample reserves regime, the floor system has become the standing operating model, with QT calibrated to maintain reserves above the scarcity threshold rather than to provide stimulus.

The Fed used to control money by making it scarce; now it controls money by paying for its abundance.

→ Framework: Liquidity, financial conditions and monetary plumbing

What it means for different economic actors

Savers. IORB indirectly determines the floor for money market fund yields, deposit rates, and short-duration bond returns. The 2022-2024 rise in IORB to 5.40% translated quickly into elevated yields on cash-equivalent vehicles, providing the highest real cash returns since 2007.

Investors. The floor system means the Fed can run a structurally larger balance sheet without compromising rate control. This has historically allowed periods of QE-driven asset inflation followed by QT-driven normalization without the corresponding loss of monetary discipline that pre-2008 frameworks would have implied.

Banks. IORB is a direct revenue source for banks, paid on hundreds of billions to trillions of dollars of reserves. This income partially offsets the cost of holding reserves rather than lending, but also creates political tensions — critics argue IORB constitutes a transfer from the Fed to large banks.

A common error is to view IORB as a minor technical detail. In practice, the IORB regime is what allows the modern Fed to combine large balance sheets with active rate management — without it, QE would have destabilized rate control.

Practical observation

Go deeper

Related questions

• How does the Fed’s balance sheet policy differ from conventional QE?
• How does the Fed control short-term rates operationally?
• Quantitative easing vs tightening
• Why did central banks abandon monetary targeting?

Frequently asked questions

Why did the Fed start paying interest on reserves in 2008?

The Emergency Economic Stabilization Act of 2008 accelerated the effective date of authority that Congress had previously granted (originally scheduled for 2011). The Fed needed IORB to maintain control of the federal funds rate as it dramatically expanded reserves through emergency lending and the early stages of QE. Without IORB, those operations would have driven the funds rate to zero regardless of the FOMC’s target — IORB allowed the Fed to expand its balance sheet without losing rate control.

How does IORB differ from the discount rate?

IORB is the rate the Fed pays banks on reserves they voluntarily hold; the discount rate is the rate the Fed charges banks that borrow at the discount window. IORB sets the floor of the policy corridor; the discount rate (technically the primary credit rate) sits above the federal funds target as a soft ceiling. In normal times, banks rarely borrow at the discount window due to stigma, while IORB shapes their everyday balance sheet decisions.

Is the floor system the only way to run modern monetary policy?

No. The pre-2008 corridor system worked successfully for decades, and some economists argue the Fed should return to it after the balance sheet shrinks sufficiently. The floor system requires structurally larger reserves and incurs ongoing IORB payments to banks. The corridor system requires more active reserve management but avoids those payments. The 2025 framework review explicitly addressed this question and concluded that the floor system, with ample reserves, would remain the standing operating model — a deliberate choice rather than an emergency holdover.

Last updated — 19 May 2026