# Interest Rate Swap: How It Works and Why Companies Use It

Published: 2026-03-22
Author: Warren Team
URL: https://www.heywarren.com/blog/swaps-interest-rate

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An interest rate swap is a derivative contract in which two parties agree to exchange interest payment streams, typically one party pays a fixed rate and the other pays a floating rate, on a notional principal amount, for a defined period. No principal changes hands; only the net difference in interest payments is exchanged. Interest rate swaps are among the most widely used derivatives in global finance, with over $350 trillion in notional outstanding, used by corporations to hedge debt costs, by banks to manage balance sheet duration, and by investors to express views on interest rate direction.

## How an Interest Rate Swap Works

**The basic structure**:
- Party A pays a **fixed rate** (e.g., 4.5% per year)
- Party B pays a **floating rate** (e.g., SOFR + 0.5%, which resets periodically)
- Both rates apply to the same **notional principal** (e.g., $100 million)
- Payments are **netted**, only the difference is exchanged

![In a plain vanilla swap, the fixed payer sends a fixed rate to the counterparty and receives a floating rate (SOFR-based) in return, only the net difference is settled in cash.](data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20660%20125%22%20width%3D%22660%22%20height%3D%22125%22%20role%3D%22img%22%3E%3Ctitle%3EFlow%20diagram%3C%2Ftitle%3E%3Crect%20width%3D%22100%25%22%20height%3D%22100%25%22%20fill%3D%22%23f8fafc%22%2F%3E%3Crect%20x%3D%2230%22%20y%3D%2225%22%20width%3D%22170%22%20height%3D%2275%22%20rx%3D%2210%22%20fill%3D%22white%22%20stroke%3D%22%232563eb%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22115%22%20y%3D%2258.5%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2214%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3ECompany%20A%3C%2Ftext%3E%3Ctext%20x%3D%22115%22%20y%3D%2278.5%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2211%22%20fill%3D%22%2364748b%22%3EPays%20fixed%204.5%25%3C%2Ftext%3E%3Cline%20x1%3D%22205%22%20y1%3D%2262.5%22%20x2%3D%22237%22%20y2%3D%2262.5%22%20stroke%3D%22%2364748b%22%20stroke-width%3D%222%22%2F%3E%3Cpolygon%20points%3D%22244%2C62.5%20235%2C57.5%20235%2C67.5%22%20fill%3D%22%2364748b%22%2F%3E%3Crect%20x%3D%22245%22%20y%3D%2225%22%20width%3D%22170%22%20height%3D%2275%22%20rx%3D%2210%22%20fill%3D%22white%22%20stroke%3D%22%232563eb%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22330%22%20y%3D%2258.5%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2214%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3ESwap%20Contract%3C%2Ftext%3E%3Ctext%20x%3D%22330%22%20y%3D%2278.5%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2211%22%20fill%3D%22%2364748b%22%3ENet%20settlement%3C%2Ftext%3E%3Cline%20x1%3D%22420%22%20y1%3D%2262.5%22%20x2%3D%22452%22%20y2%3D%2262.5%22%20stroke%3D%22%2364748b%22%20stroke-width%3D%222%22%2F%3E%3Cpolygon%20points%3D%22459%2C62.5%20450%2C57.5%20450%2C67.5%22%20fill%3D%22%2364748b%22%2F%3E%3Crect%20x%3D%22460%22%20y%3D%2225%22%20width%3D%22170%22%20height%3D%2275%22%20rx%3D%2210%22%20fill%3D%22white%22%20stroke%3D%22%232563eb%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22545%22%20y%3D%2258.5%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2214%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3ECompany%20B%3C%2Ftext%3E%3Ctext%20x%3D%22545%22%20y%3D%2278.5%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2211%22%20fill%3D%22%2364748b%22%3EPays%20SOFR%20%2B%200.5%25%3C%2Ftext%3E%3C%2Fsvg%3E)

*In a plain vanilla swap, the fixed payer sends a fixed rate to the counterparty and receives a floating rate (SOFR-based) in return, only the net difference is settled in cash.*

**Semi-annual payment example**:
- Notional: $100 million
- Fixed rate: 4.5% annually = 2.25% per semi-annual period
- Floating rate (SOFR + 0.5%): If SOFR is 5.0%, floating = 5.5% annually = 2.75% semi-annual

Net settlement: Fixed payer owes 2.25% × $100M = $2.25M; floating payer owes 2.75% × $100M = $2.75M
Net cash flow: Floating payer pays $0.5M net to fixed payer for this period

## Why Companies Use Interest Rate Swaps

**Converting floating debt to fixed**: A company with a floating-rate bank loan (e.g. SOFR + 200bps) faces rising payment risk if rates increase. By entering a "pay fixed, receive floating" swap, the company effectively converts the floating-rate loan to a fixed rate, the floating payments from the swap offset the loan's floating payments, leaving the company with predictable fixed-rate exposure.

**Converting fixed bonds to floating**: A company that issued fixed-rate bonds may want floating-rate exposure (if it expects rates to fall, or if its revenues are floating-rate indexed). A "receive fixed, pay floating" swap converts the bond's fixed coupon into a floating-rate liability.

**Asset-liability matching for banks**: Banks have predominantly floating-rate assets (variable-rate loans) funded by a mix of fixed and floating liabilities. Swaps allow banks to adjust their interest rate sensitivity (duration mismatch) without restructuring the underlying balance sheet.

**Speculation/investment**: Hedge funds and proprietary trading desks use interest rate swaps to express directional views on rates. A fund expecting rates to fall would "receive fixed", as rates fall, fixed receipts become more valuable relative to floating payments.

## Vanilla Swap vs. Other Swap Types

The "plain vanilla" interest rate swap (fixed for floating) is the most common, but several variations exist:

![The plain vanilla fixed-for-floating swap is the most common, but basis, cross-currency, and amortising swaps serve distinct hedging needs.](data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20760%20211%22%20width%3D%22760%22%20height%3D%22211%22%20role%3D%22img%22%3E%3Ctitle%3EHierarchy%3C%2Ftitle%3E%3Crect%20width%3D%22100%25%22%20height%3D%22100%25%22%20fill%3D%22%23f8fafc%22%2F%3E%3Crect%20x%3D%22300%22%20y%3D%2220%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22%232563eb%22%2F%3E%3Ctext%20x%3D%22380%22%20y%3D%2254%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2214%22%20font-weight%3D%22700%22%20fill%3D%22white%22%3EInterest%20Rate%20Swaps%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20110%20105.5%20L%20110%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%2230%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22110%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EVanilla%3C%2Ftext%3E%3Ctext%20x%3D%22110%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EFixed%20for%20floating%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20290%20105.5%20L%20290%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%22210%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22290%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EBasis%20Swap%3C%2Ftext%3E%3Ctext%20x%3D%22290%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EFloat%20for%20float%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20470%20105.5%20L%20470%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%22390%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22470%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3ECross-Currency%3C%2Ftext%3E%3Ctext%20x%3D%22470%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EFX%20%2B%20rate%20hedge%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20650%20105.5%20L%20650%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%22570%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22650%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EAmortising%3C%2Ftext%3E%3Ctext%20x%3D%22650%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EDeclining%20notional%3C%2Ftext%3E%3C%2Fsvg%3E)

*The plain vanilla fixed-for-floating swap is the most common, but basis, cross-currency, and amortising swaps serve distinct hedging needs.*

| Swap Type | Fixed Party | Floating Party | Use Case |
|---|---|---|---|
| Vanilla (pay fixed) | Pays fixed | Receives floating | Hedge floating-rate debt |
| Vanilla (receive fixed) | Receives fixed | Pays floating | Hedge fixed-rate bond liability |
| Basis swap | Pays one floating rate | Pays different floating rate | Hedge SOFR vs. Prime rate mismatch |
| Cross-currency swap | Pays fixed in currency A | Receives fixed in currency B | Hedge FX + rate exposure simultaneously |
| Amortising swap | Notional decreases over time | Mirrors amortising loan balance | Hedge amortising [term loan](/blog/what-is-a-term-loan) |

## Swap Pricing: The Fixed Rate Determination

The fixed rate in a swap is set at inception so that the swap has **zero initial fair value**, neither party is paying a premium to enter.

The fixed rate is calculated as the rate that equates the present value of fixed payments to the present value of expected floating payments, based on the [current yield](/blog/current-yield-on-bond-formula) curve.

**Simplified example**:
- 5-year swap
- SOFR forward rates: Year 1: 5.0%, Year 2: 4.8%, Year 3: 4.5%, Year 4: 4.2%, Year 5: 4.0%
- Present value of all floating payments (discounted appropriately)
- The fixed rate that equates to this PV = approximately 4.5%

As market rates change after inception, the swap gains or loses value, the mark-to-market value is the difference between the present value of fixed vs. expected floating payments under the new rate environment.

## SOFR: The Floating Rate Benchmark

Before 2023, most USD swaps referenced **LIBOR** (London Interbank Offered Rate) as the floating leg. Following the LIBOR scandal (manipulation by banks) and its discontinuation, USD markets transitioned to **SOFR** (Secured Overnight Financing Rate), a rate published by the [Federal Reserve](https://www.federalreserve.gov/) Bank of New York based on actual overnight repo transactions.

SOFR is considered more robust than LIBOR because it's based on real transactions rather than bank survey submissions. Most new USD interest rate swaps now reference SOFR.

## Counterparty Risk and Central Clearing

Pre-2008, most interest rate swaps were bilateral over-the-counter (OTC) transactions, the two parties were exposed to each other's default risk for the duration of the swap. Post-crisis regulation (Dodd-Frank in the US, EMIR in Europe) mandated **central clearing** of standardised swaps:

![Post-2008 regulation shifted standardised swaps from bilateral OTC exposure to central clearing through a CCP, reducing counterparty risk.](data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20800%20149%22%20width%3D%22800%22%20height%3D%22149%22%20role%3D%22img%22%3E%3Ctitle%3ETimeline%3C%2Ftitle%3E%3Crect%20width%3D%22100%25%22%20height%3D%22100%25%22%20fill%3D%22%23f8fafc%22%2F%3E%3Cline%20x1%3D%22137.5%22%20y1%3D%2255%22%20x2%3D%22662.5%22%20y2%3D%2255%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%223%22%2F%3E%3Ccircle%20cx%3D%22137.5%22%20cy%3D%2255%22%20r%3D%2224%22%20fill%3D%22white%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22137.5%22%20y%3D%2260%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2215%22%20font-weight%3D%22700%22%20fill%3D%22%230f172a%22%3E1%3C%2Ftext%3E%3Ctext%20x%3D%22137.5%22%20y%3D%22101%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2212%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EPre-2008%3C%2Ftext%3E%3Ctext%20x%3D%22137.5%22%20y%3D%22119%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EBilateral%20OTC%2C%20direct%20cou%E2%80%A6%3C%2Ftext%3E%3Ccircle%20cx%3D%22312.5%22%20cy%3D%2255%22%20r%3D%2224%22%20fill%3D%22%232563eb%22%20stroke%3D%22%232563eb%22%20stroke-width%3D%223%22%2F%3E%3Ctext%20x%3D%22312.5%22%20y%3D%2260%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2215%22%20font-weight%3D%22700%22%20fill%3D%22white%22%3E2%3C%2Ftext%3E%3Ctext%20x%3D%22312.5%22%20y%3D%22101%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2212%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3E2008%20Crisis%3C%2Ftext%3E%3Ctext%20x%3D%22312.5%22%20y%3D%22119%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3ECounterparty%20failures%20exp%E2%80%A6%3C%2Ftext%3E%3Ccircle%20cx%3D%22487.5%22%20cy%3D%2255%22%20r%3D%2224%22%20fill%3D%22white%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22487.5%22%20y%3D%2260%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2215%22%20font-weight%3D%22700%22%20fill%3D%22%230f172a%22%3E3%3C%2Ftext%3E%3Ctext%20x%3D%22487.5%22%20y%3D%22101%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2212%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EDodd-Frank%20%2F%20EMIR%3C%2Ftext%3E%3Ctext%20x%3D%22487.5%22%20y%3D%22119%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EClearing%20mandates%20enacted%3C%2Ftext%3E%3Ccircle%20cx%3D%22662.5%22%20cy%3D%2255%22%20r%3D%2224%22%20fill%3D%22white%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22662.5%22%20y%3D%2260%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2215%22%20font-weight%3D%22700%22%20fill%3D%22%230f172a%22%3E4%3C%2Ftext%3E%3Ctext%20x%3D%22662.5%22%20y%3D%22101%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2212%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3ECentral%20Clearing%3C%2Ftext%3E%3Ctext%20x%3D%22662.5%22%20y%3D%22119%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3ECCP%20interposes%2C%20margin%20co%E2%80%A6%3C%2Ftext%3E%3C%2Fsvg%3E)

*Post-2008 regulation shifted standardised swaps from bilateral OTC exposure to central clearing through a CCP, reducing counterparty risk.*

**Central clearing**: A central counterparty (e.g. [CME Group](https://www.cmegroup.com/), LCH.Clearnet) interposes itself between buyer and seller, each party faces the CCP, not each other. The CCP collects margin (initial margin + variation margin) from both sides.

This dramatically reduces bilateral counterparty risk but concentrates risk in a few systemically important CCPs, which are now subject to their own rigorous regulatory requirements.

## Conclusion

Interest rate swaps are the most widely used tool for managing interest rate exposure in corporate finance and banking. The basic mechanics, exchanging fixed for floating payments on a notional principal, with net settlement, are straightforward, but the applications are broad: hedging debt costs, managing duration, expressing rate views. Understanding swap economics helps explain why companies' actual interest expense differs from their nominal debt costs, and why banks' net interest margins change with the rate environment. See our guide on [yield spread premium](/blog/yield-spread-premium) for related fixed income risk concepts.

Warren at [heywarren.com](https://heywarren.com) helps investors and treasury professionals understand interest rate derivatives, hedging strategies, and the impact of rate swaps on corporate and bank financial statements.

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## Related Reading

**More from Warren**:
- [Credit Default Swap: What It Is and How Credit Risk Is Priced](/blog/credit-default-swap)
- [Yield Spread Premium: What It Is and How It Affects Mortgage Costs](/blog/yield-spread-premium)
- [What Does a Corporate Treasurer Do? Role, Responsibilities, and Skills](/blog/corporate-treasurer)

**Authoritative sources**:
- [CME Group, Interest Rate Swaps](https://www.cmegroup.com/trading/interest-rates/swaps.html)
- [Federal Reserve Bank of New York, SOFR](https://www.newyorkfed.org/markets/reference-rates/sofr)
- [ISDA, Derivative Documentation Standards](https://www.isda.org/books/isda-master-agreement/)