Your bank doesn’t have a branch in every country. When you wire $10,000 to London, your local bank can’t just walk it over to the recipient’s bank. Instead, it hands the money to another bank, which hands it to another bank, which eventually gets it there.

This is correspondent banking. It’s the hidden infrastructure that moves most international money and why your wire costs $50 and takes days to arrive.

The basic mechanics

Correspondent banking works like a chain of trusted intermediaries. Banks that can’t directly reach each other use mutual relationships with banks that can.

Say your bank (Bank A) wants to send money to a bank in Germany (Bank C). Bank A doesn’t have a direct relationship with Bank C. But both banks have relationships with a large international bank (Bank B). So Bank A sends the payment to Bank B with instructions, Bank B forwards it to Bank C, and Bank C credits the final recipient.

Each bank in the chain takes a fee, adds processing time and introduces another point of potential failure.

Nostro and vostro accounts

The system runs on pre-funded accounts that banks maintain with each other. The names are confusing: nostro (“our” in Latin) and vostro (“your” in Latin).

When JP Morgan holds an account at Deutsche Bank, JP Morgan calls it their “nostro account at Deutsche Bank.” Deutsche Bank calls the same account “JP Morgan’s vostro account with us.”

It’s the same account, just from different perspectives.

These accounts must be funded in advance. If JP Morgan wants to send euros through Deutsche Bank, they need euros sitting in their nostro account. If the account runs dry, payments stop until it’s replenished.

This creates a massive capital requirement. Large correspondent banks maintain funded accounts in dozens of currencies across hundreds of relationships.

Why international wires take 1-5 days

Every hop in the correspondent chain adds delay:

Cut-off times: Each bank processes international payments at specific times. Miss the 2 PM cut-off in New York, and your payment waits until tomorrow.

Time zones: A payment initiated Friday afternoon in California might not start processing in Europe until Monday morning.

Compliance screening: Each bank screens payments for sanctions, money laundering and fraud. Complex payments can sit in queues for manual review.

Nostro reconciliation: Banks must reconcile their nostro accounts daily. Discrepancies can freeze payments until resolved.

Weekend gaps: Most correspondent banks don’t process on weekends. A Friday payment often sits idle until Monday.

The payment isn’t actually “traveling” for days. It’s sitting in queues, waiting for business hours and passing compliance checks.

Where the fees come from

Each bank in the correspondent chain charges for their service:

Originating bank fee: $25-45 for initiating the wire. This covers their compliance screening, nostro management and correspondent relationship costs.

Intermediary bank fees: $10-25 per hop. If your payment routes through two correspondent banks, that’s potentially $50 in hidden fees.

Receiving bank fee: $10-20 for crediting the final recipient. Often deducted from the payment amount.

FX spreads: Each currency conversion includes a spread, typically 0.5-2% above the interbank rate.

A $10,000 payment can easily incur $100+ in total fees across the chain. The fee structure is opaque because it’s distributed across multiple institutions.

The concentration problem

Correspondent banking has consolidated around a small number of global banks. A handful of major institutions now process a disproportionate share of international payments.

This creates systemic dependencies. When a major correspondent bank exits a relationship (due to compliance costs or strategic shifts), entire regions can lose payment connectivity.

After 2008, regulatory pressure caused many banks to exit correspondent relationships in higher-risk jurisdictions. Some Caribbean and African countries lost significant payment connectivity, making international transfers slower and more expensive.

Why this system persists

Despite the inefficiencies, correspondent banking is hard to replace:

Regulatory acceptance: Central banks and regulators understand correspondent banking. Alternative systems face unclear regulatory treatment.

Universal reach: The correspondent network can reach virtually any bank worldwide. New systems start with limited coverage.

Settlement finality: Correspondent payments settle in central bank money, the safest form of settlement. Alternative systems often settle in commercial bank money or require additional conversion steps.

Integration costs: Banks have spent decades building systems around correspondent banking. Message formats (SWIFT), reconciliation processes and compliance workflows all assume this model.

Network effects: The value of a payment network increases with the number of participants. Correspondent banking has maximum network effects after decades of growth.

What’s changing

Several developments are chipping away at correspondent banking:

Central bank digital currencies (CBDCs): Could enable direct bank-to-bank settlement without correspondent intermediaries.

Blockchain-based settlement: Some banks are experimenting with tokenized deposits for faster cross-border settlement.

Bilateral agreements: Payment systems in different countries are connecting directly (linking domestic real-time systems).

Stablecoin infrastructure: Dollar-denominated stablecoins can move internationally without traditional correspondent chains.

But these alternatives face adoption, regulatory and technical hurdles that will take years to resolve.

The tradeoff

Correspondent banking is expensive, slow and concentrated. It’s also proven, regulated and universal. This isn’t a system anyone designed. It evolved over decades to solve real problems around trust, settlement and regulatory compliance.

The hidden network of nostro accounts, compliance checks and batched processing creates the delays and fees that frustrate consumers. But it also enables a small regional bank in Ohio to send money safely to a bank in Thailand.

That’s the tradeoff. And it’s why replacing this system is harder than building a better app.