What Is Required Reserve Ratio? | How Banks Hold Back Cash

A required reserve ratio is the deposit share a bank must keep as reserves, shaping how much money can move into loans.

“Required reserve ratio” sounds technical until you tie it to a simple rule: a slice of certain deposits must stay parked as reserves. That slice can widen or shrink, and banks adjust lending, pricing, and liquidity plans around it.

You’ll get the definition, the math, what counts as reserves, and how the rule shows up in real banking. You’ll also see why the idea still matters even where reserve requirements sit at 0% right now.

Required Reserve Ratio For Banks: What It Controls

The required reserve ratio (often called the reserve ratio) is the percentage of certain deposit liabilities that a bank must hold as reserves. Reserves are funds the bank keeps ready, either as cash in its vault or as balances held at the central bank.

It’s a minimum buffer. If the ratio is 10%, a bank with $1,000,000 in in-scope deposits must hold $100,000 in required reserves. The rest can be used for lending, buying securities, or holding extra reserves above the minimum.

What Is Required Reserve Ratio? In Plain Terms

Plainly: it’s the “must-keep” slice of deposits. The bank can still lend. It just can’t lend every last dollar of in-scope deposits because part must stay in reserve form.

Reserve rules also aren’t capital rules. Capital is owner funding that absorbs losses. Reserves are liquid assets tied to deposit totals.

What Counts As Reserves

Vault cash can count, yet modern reserve systems lean heavily on balances held at the central bank. Most rules recognize reserves that are immediately available and clearly measurable.

Common reserve components

• Vault cash: Currency and coin the bank holds on site.
• Central bank balances: Funds in the bank’s account at the central bank.
• Eligible pass-through arrangements: In some systems, smaller institutions meet requirements through a correspondent, based on local rules.

Which Deposits The Ratio Applies To

Reserve requirements rarely apply to every liability on a bank’s balance sheet. Many systems center on transaction deposits, like checking accounts, because they can be withdrawn fast and are used for payments.

Some systems also apply requirements to savings deposits, time deposits, or certain foreign-currency liabilities. Always identify the “base” before you do any math.

How The Required Reserve Ratio Is Calculated

Required reserves = Reservable deposits × Required reserve ratio

A quick walk-through

Say a bank has $50,000,000 in reservable deposits and the ratio is 10%.

• Required reserves: $50,000,000 × 0.10 = $5,000,000
• If the bank holds $6,200,000 in eligible reserves, it has $1,200,000 in excess reserves.
• If it holds $4,300,000, it’s short by $700,000 and must close that gap fast.

To close a shortfall, a bank can bring in cash, move funds into its central bank account, borrow reserves overnight, or reduce reservable deposits. The choice depends on market access and local rules.

Why Central Banks Use Reserve Requirements

Reserve ratios exist for practical reasons, and different countries weigh them differently.

Liquidity buffer

A minimum reserve level can lower day-to-day cash stress and reduce the odds of missing payments.

Money market steering

Reserve rules can shape demand for central bank balances, which can help with short-term rate control in some operating systems.

Credit growth brake or release valve

Raising the ratio can force banks to hold more reserves per dollar of deposits. Lowering it frees funds and can make balance-sheet expansion easier when other limits aren’t binding first.

How Reserve Requirements Work In The United States Today

In the U.S., the Federal Reserve announced in March 2020 that it reduced reserve requirement ratios to 0% for all depository institutions, effective March 26, 2020. That change removed reserve requirements under the Fed’s setup at that time. The Fed maintains its official page on Reserve Requirements.

Even with a 0% setting, the concept still helps in three ways:

• Policy can shift: The legal authority for reserve requirements remains part of the policy rulebook.
• Global use continues: Many central banks keep a positive ratio and adjust it as conditions change.
• Liquidity still needs managing: Banks still hold liquid buffers for settlement, withdrawals, and internal risk limits.

Where People Get Tripped Up

The term sounds like a single, universal number. In practice, it’s a rule with moving parts.

Mixing up reserves with capital

Reserves are liquid assets. Capital is owner funding that absorbs losses. A bank can be well capitalized and still face liquidity stress.

Assuming one ratio applies to every deposit

Many systems use tiers and exemptions. That’s why a bank’s “effective” ratio can differ from a headline rate.

Thinking reserves must be physical cash

Central bank balances often do the heavy lifting. Vault cash still matters for branches and ATMs, yet it is only one piece.

Quick Reference: Core Pieces Of A Reserve Requirement Regime

The table below gives you a compact map of what to check when you’re trying to understand a country’s required reserve ratio and how it bites.

Element	What It Means	What To Watch
Reservable deposit base	Which deposits count toward the calculation	Transaction vs savings vs time deposits
Ratio level	The required percentage applied to the base	Single rate or tiered rates
Exemption amount	A deposit amount not subject to the requirement	Changes by rule or by calendar year
Low tranche band	A deposit band that may face a lower rate	Band size and rate applied
Maintenance period	Window when compliance is measured	Daily average vs end-of-day points
Eligible reserves	Assets that count toward meeting the rule	Vault cash, central bank balances, other eligible items
Penalty for shortfall	Cost of missing the required level	Penalty rate, reporting, escalation
Remuneration	Whether reserves earn interest	Rate paid on required vs excess reserves
Operational link to policy rate	How reserve demand ties into rate control	Corridor vs floor systems, role of open market ops

How A Reserve Ratio Can Shape Lending

Textbook stories make it sound mechanical: deposits arrive, banks keep the required share, then they lend the rest. Real banking is more flexible. Banks lend based on credit demand, pricing, capital, liquidity plans, and risk limits.

Still, a higher required reserve ratio can make each dollar of in-scope deposits “heavier” because the bank must finance extra reserves that can’t be used for higher-yield assets. That can push loan pricing up, tighten underwriting, or shift the bank toward other funding sources.

A lower ratio can make growth cheaper, as long as other limits don’t bind first.

Say two banks each have $100 million in transaction deposits. In a system with a 10% requirement, each needs $10 million in eligible reserves tied to that base. If one bank already holds a large central bank balance, it may not feel much strain. If the other runs lean and relies on overnight borrowing, the same ratio can raise its day-to-day funding cost.

This is why you’ll hear bankers talk about “binding” requirements. A rule binds when it forces a change in behavior. When plenty of excess reserves exist, a ratio can sit in the background. When excess reserves are scarce, the same ratio can change loan pricing, deposit strategy, and even which customers the bank prefers to serve.

Required Reserve Ratio Changes And What They Signal

When a central bank changes the ratio, it is reacting to liquidity conditions and credit growth. The direct effect depends on the in-scope deposit base and how much excess liquidity banks already hold.

When the ratio rises

• Banks may chase reserves, pushing up short-term funding rates.
• Loan growth can cool if balance-sheet room tightens.
• Some banks may shift toward longer-term funding or different deposit types.

When the ratio falls

• Compliance pressure eases and reserve demand drops.
• Banks can redirect funds toward loans or other assets.
• Money market rates can soften if reserves become easier to obtain.

How Reserve Rules Are Written And Enforced

Reserve requirements only work when banks can measure them cleanly and supervisors can verify them. Most systems spell out:

• what counts as reservable deposits,
• which assets count as eligible reserves,
• the maintenance period and reporting schedule,
• what happens when a bank misses the requirement.

If you want to see the official structure in the U.S., read 12 CFR Part 204, the regulation that implements reserve requirements for depository institutions.

Second Table: What A Ratio Change Can Do

This table links a reserve ratio move to common bank responses and market signals.

Policy move	Likely bank response	What you might notice
Ratio increase with low excess reserves	Borrow reserves, slow asset growth	Higher overnight rates, tighter loan terms
Ratio increase with high excess reserves	Small shift in funding routine	Muted market reaction
Ratio cut during a liquidity squeeze	Use freed reserves to meet payments	Funding stress eases
Ratio cut during steady growth	Room for faster balance-sheet expansion	More loan offers, softer funding pressure
Tighter rules on what counts as reserves	Shift into central bank balances	Demand for settlement balances rises
Interest paid on reserves raised	Hold more reserves willingly	Less chase for risky yield
Maintenance period shortened	More active daily liquidity management	More short-term borrowing

How To Answer This Topic In A Study Setting

If you’re writing an assignment, keep your answer tight and structured.

One sentence definition

The required reserve ratio is the share of reservable deposits that a bank must hold as reserves, set by the monetary authority.

Three-step calculation

• Identify the reservable deposit base.
• Multiply by the ratio to get required reserves.
• Compare required reserves with actual reserves to find excess reserves or a shortfall.

That structure keeps you clear and avoids drifting into vague “money multiplier” talk when the question is only asking for the rule and the math.