An interest rate swap is a private contract in which two parties agree to exchange interest payments on a set dollar amount for a defined period, with one side paying a fixed rate and the other paying a rate that floats with the market. The dollar figure used to calculate those payments, called the notional, never actually changes hands, so neither party is lending money to the other. These contracts trade off-exchange, which is why federal regulators impose clearing, reporting, and margin rules on them.
How the Payments Actually Work
Every swap has two “legs.” The fixed leg locks in a single rate for the life of the deal. The floating leg resets periodically against a market benchmark. On each payment date, the two sides don’t wire the full amount they each owe. They net the obligations, and whoever owes more pays only the difference. That single net payment replaces two gross transfers, cutting both transaction costs and the credit exposure each side carries on any given settlement date.1Federal Reserve Bank of New York. Miller’s Presentation on Netting
All of the interest math sits on top of the notional principal. If two parties agree on a $10 million notional and a 5% fixed rate, the fixed-rate payer owes $500,000 per year before day-count adjustments. The floating-rate payer owes whatever the benchmark rate produces when applied to that same $10 million. The notional itself never moves between accounts and creates no debt. It is a reference number, nothing more. This is what distinguishes a swap from a loan: in a loan, the principal is real money that must be repaid; in a swap, it exists only to compute what each side owes the other.
Common Swap Structures
The plain vanilla swap is the workhorse of the market. One party pays a fixed rate, the other pays a floating rate tied to a benchmark. A corporate treasurer who has borrowed at a floating rate and wants certainty can enter a plain vanilla swap as the fixed-rate payer, effectively converting floating-rate debt into fixed-rate debt without refinancing the underlying loan.
A basis swap exchanges one floating rate for another. Neither leg is fixed, and the payoff depends on the spread between two benchmarks. One leg might reference the Secured Overnight Financing Rate while the other references the fed funds rate. This structure is useful when a party’s assets earn interest tied to one index but its liabilities are tied to a different one.
A forward swap (or forward-starting swap) locks in terms today but delays the start of actual payments to a future effective date. The parties agree now on the fixed rate, notional, and payment schedule, but no interest accrues until that later date arrives. A borrower can use this to hedge a future debt issuance months before the bonds are priced.
The Floating Benchmark and How It Resets
For U.S. dollar swaps, the floating leg now typically references the Secured Overnight Financing Rate (SOFR). LIBOR panel submissions ended on June 30, 2023, and U.S. banking regulators told supervised institutions to stop writing new LIBOR contracts by the end of 2021.2Federal Reserve Bank of New York. Alternative Reference Rates Committee – SOFR Transition SOFR is based on actual overnight Treasury repo transactions, which makes it harder to manipulate than the old survey-based LIBOR.
Because SOFR is an overnight rate, applying it across a three- or six-month interest period requires a compounding method. The common conventions calculate the rate “in arrears,” meaning the final number isn’t known until the period ends. To give both sides time to settle the payment, three conventions have developed:
- Payment delay: Interest accrues through the end of the period, but payment is made a few business days later.
- Lockout: The SOFR rate is frozen for the last few days of the period at whatever rate was observed a few days before period end.
- Lookback: Each day’s interest uses the SOFR rate from a set number of business days earlier, shifting the observation window backward so the calculation can be completed before payment is due.3Federal Reserve Bank of New York. An Updated User’s Guide to SOFR
The confirmation for each trade specifies which compounding method applies, along with reset frequency, payment frequency, and the day-count convention for each leg. Fixed legs commonly use 30/360, which assumes every month has 30 days and every year has 360. Floating legs typically use Actual/360, counting actual calendar days over a 360-day year. These conventions slightly change the dollar amount of each payment.
Who Is Allowed to Enter One
Federal law restricts off-exchange swaps to “eligible contract participants” (ECPs). The threshold varies by entity type:
- Corporations and other business entities: More than $10 million in total assets. Entities hedging commercial risk qualify with a net worth above $1 million.4Office of the Law Revision Counsel. 7 USC 1a – Definitions
- Individuals: More than $10 million invested on a discretionary basis, or more than $5 million if the swap hedges an existing risk.4Office of the Law Revision Counsel. 7 USC 1a – Definitions
- Commodity pools: Total assets above $5 million, operated by a registered person.
- Employee benefit plans: Total assets above $5 million, or investment decisions made by a registered investment adviser or financial institution.
- Government entities: Own and invest at least $50 million on a discretionary basis.
Entities that fall below the ECP thresholds cannot enter bilateral swaps directly, but they can still access interest-rate hedging through exchange-traded futures and options, which come with different protections.
The ISDA Documentation That Governs the Trade
Nearly every interest rate swap is documented under a set of contracts published by the International Swaps and Derivatives Association. The ISDA Master Agreement is the umbrella contract between two parties, covering representations, events of default, and early termination mechanics. It applies to every trade the two parties do with each other, so foundational terms aren’t renegotiated for each new swap.5International Swaps and Derivatives Association. Legal Guidelines for Smart Derivatives Contracts – The ISDA Master Agreement The Schedule is where the parties customize the pre-printed form: choice of governing law, cross-default thresholds, and other tailored terms. Each individual trade is then documented in a Confirmation that captures the notional, fixed rate, floating benchmark, effective date, termination date, payment dates, and day-count conventions.6U.S. Securities and Exchange Commission. ISDA Master Agreement, Schedules, and Transaction Confirmation
When the parties agree to post collateral against their mark-to-market exposure, they sign a Credit Support Annex (CSA). The CSA specifies acceptable collateral types (cash, government bonds), margin call frequency, minimum transfer amounts, and thresholds below which no collateral moves.
Clearing, Reporting, and Margin Rules
The Dodd-Frank Act made it illegal to enter a swap that is required to be cleared without submitting it to a registered derivatives clearing organization.7Office of the Law Revision Counsel. 7 USC 2 – Clearing Requirement The Commodity Futures Trading Commission (CFTC) determines which swap classes must be cleared, and for U.S. dollar interest rate swaps the mandate covers overnight index swaps referencing SOFR and fed funds across a range of maturities.8eCFR. 17 CFR 50.4 – Classes of Swaps Required to Be Cleared When a swap is cleared, a central clearinghouse steps between the two original parties, becoming the buyer to every seller and the seller to every buyer, which largely eliminates the risk that a counterparty default leaves the other side holding a worthless contract.
Swaps outside the mandate (because of structure, currency, or the end-user exemption) remain bilateral and carry higher counterparty risk. Whether cleared or not, every swap must be reported to a swap data repository. Swap dealers and major swap participants report creation data by the end of the next business day; non-dealer counterparties get an extra day.9eCFR. 17 CFR Part 45 – Swap Data Recordkeeping and Reporting Requirements Material changes over the life of the trade, including amendments, partial terminations, and assignments, must also be reported.10Legal Information Institute. Dodd-Frank Title VII – Wall Street Transparency and Accountability
For uncleared swaps, CFTC rules require counterparties to exchange variation margin daily. The covered swap entity must collect or post that amount by the business day after execution, and then continue each business day until the swap terminates.11eCFR. 17 CFR 23.153 – Collection and Posting of Variation Margin Variation margin reflects the day-to-day change in the swap’s market value. If rates move against you, you post collateral; if they move in your favor, you receive it.
Initial margin is a separate buffer meant to cover potential losses during the window between a counterparty’s default and close-out. It applies only when both sides have “material swaps exposure,” defined as an average month-end aggregate notional of uncleared swaps exceeding $8 billion, measured over March, April, and May.12GovInfo. 17 CFR 23.151 – Definitions Applicable to Margin Requirements Even when initial margin is required, no exchange happens until the aggregate exposure between the two affiliate groups exceeds $50 million. For most corporate end users, these thresholds mean initial margin never kicks in, though variation margin is essentially universal on uncleared swaps with a regulated dealer.
Tax Treatment
The IRS treats an interest rate swap as a “notional principal contract.” Periodic net payments are included in or deducted from gross income in the taxable year they relate to, regardless of when cash actually changes hands.13eCFR. 26 CFR 1.446-3 – Notional Principal Contracts Net payments received increase taxable income, and net payments made are deductible, spread ratably over each accrual period.
Termination payments follow a different rule. Under 26 U.S.C. ยง 1234A, gain or loss from the cancellation, expiration, or other termination of a right or obligation with respect to a capital asset is treated as gain or loss from the sale of a capital asset.14Office of the Law Revision Counsel. 26 USC 1234A – Gains or Losses from Certain Terminations If the swap qualifies as a hedging transaction and was properly identified as one, both gains and losses on termination are ordinary rather than capital. The identification requirement matters. A company that fails to designate its swap as a hedge in its books by the deadline can lose ordinary treatment on a termination loss even if the swap was economically a hedge from day one.
Default Triggers That Can End a Swap Early
The ISDA Master Agreement lists specific events that give the non-defaulting party the right to terminate all outstanding swaps with a counterparty. The core triggers include failure to pay (missing a scheduled payment that isn’t cured by the next business day after notice), bankruptcy or insolvency, credit support default (failing to meet obligations under the CSA), material misrepresentation, and breach of an obligation under the Master Agreement that isn’t cured within 30 days after notice.15U.S. Securities and Exchange Commission. ISDA 2002 Master Agreement
Cross-default deserves its own note. If elected in the schedule, a default on other debt above a specified dollar threshold can trigger termination of every swap. A missed payment on an unrelated credit facility above the threshold gives the counterparty the right to close out every trade. Negotiating that threshold in the schedule is one of the most consequential decisions in the whole documentation package.
How Swaps End
Natural Expiration
The simplest ending: the swap reaches the scheduled termination date stated in the confirmation. The parties settle the final accrual period’s net payment and all obligations cease. No notice is required.
Early Termination and Close-Out
When an event of default or termination event occurs, the non-defaulting party (or in some cases either party) can designate an early termination date. All outstanding trades under the Master Agreement are then closed out and replaced by a single net payment.5International Swaps and Derivatives Association. Legal Guidelines for Smart Derivatives Contracts – The ISDA Master Agreement
The amount is calculated using the “Close-out Amount” methodology. The determining party estimates the losses or costs it would incur, or the gains it would realize, in replacing the terminated trades or obtaining their economic equivalent under current market conditions. That calculation can draw on dealer quotes, market data, or internal models, but the determining party must act in good faith and use commercially reasonable procedures.16International Swaps and Derivatives Association. ISDA Close-out Amount Protocol The result is not simply the current market value of the swap. It can include the cost of replacing hedge positions and the credit quality of the determining party at the time. For an event of default, unpaid amounts owed to the non-defaulting party are added to the calculation and amounts owed to the defaulting party are subtracted.
Parties can also agree to terminate a swap early by mutual consent, without any default. They typically negotiate a cash settlement reflecting the swap’s current mark-to-market value, either by agreeing on the number directly or using an independent valuation.
Novation
Novation lets one party exit by transferring its entire position to a new counterparty. Under the ISDA Novation Protocol, three things must line up: the departing party (the transferor) proposes the transfer, the incoming party (the transferee) affirms the details, and the remaining counterparty consents. The transfer is not legally binding until that consent is received.17International Swaps and Derivatives Association. Additional Provisions for Consent to, and Confirmation of, Transfer by Novation of OTC Derivative Transactions If the remaining party withholds consent or doesn’t respond by the cutoff, the protocol provides that the transferor and transferee will instead book a new trade between themselves. Once a novation completes, the transferor is fully released from all future obligations and the transferee steps into the original trade as if it had been there from the start.
The remaining counterparty’s consent is not a formality. That party is agreeing to take on credit exposure to an entirely different entity, so it will evaluate the incoming party’s creditworthiness before signing off. Novations can stall here in practice, particularly if the replacement party is less creditworthy than the original.