A swap works by locking two parties into a contract to exchange cash flows over a set period, calculated against a reference amount of money called the notional that never changes hands. One side typically pays a fixed rate; the other pays a rate that floats with a market benchmark. On each scheduled date, the two obligations are netted so only the difference actually moves. Standardized ISDA paperwork governs the relationship, collateral gets posted along the way to cover market swings, and for most interest rate swaps a central counterparty steps between the two sides to absorb default risk. That is the shape of the whole thing. The rest is detail.
What a Swap Actually Is
Every swap is built from a few defining variables. The notional principal is the reference amount used to calculate payments. A $50 million notional drives the math on both legs, but nobody sends $50 million anywhere. It just sets the scale.
The effective date is when the contract activates and interest starts accruing. The termination date is when it expires. Most swaps run anywhere from two to thirty years. A corporation hedging a ten-year bond issue will usually match the swap term to the bond’s maturity.
One party, the fixed-rate payer, locks in a set percentage for the life of the deal. The other pays a floating rate tied to a benchmark. Since the retirement of LIBOR, the dominant U.S. benchmark is the Secured Overnight Financing Rate (SOFR), which reflects overnight borrowing costs in the Treasury repo market. On each reset date, the floating rate adjusts to wherever SOFR sits. The floating payer’s obligation moves; the fixed payer’s stays put.
Who Is Allowed to Enter One
Federal law restricts swap participation to entities and individuals who qualify as “eligible contract participants.” If you don’t meet the threshold, you generally cannot legally enter an off-exchange swap.
- Corporations and other business entities need total assets over $10 million, or a net worth over $1 million if the swap is connected to the entity’s business operations or risk management.
- Commodity pools need total assets over $5 million and must be operated by a regulated person.
- Employee benefit plans need total assets over $5 million, or investment decisions made by a regulated investment adviser.
- Individuals need over $10 million in discretionary investments, or over $5 million if entering the swap to manage risk tied to an existing asset or liability.
- Government entities must own and invest at least $50 million on a discretionary basis.
Financial institutions, insurance companies, and registered investment companies qualify automatically regardless of asset size.1Office of the Law Revision Counsel. 7 USC 1a – Definitions
The ISDA Paperwork That Governs the Trade
Before any money moves, the parties build a legal scaffolding out of standardized documents published by the International Swaps and Derivatives Association. The documentation has four layers, and mishandling any of them creates real legal exposure.
Master Agreement and Schedule
The ISDA Master Agreement is the foundation. It governs every swap the two parties will ever do with each other, covering default events, termination rights, and the mechanics of close-out netting. The current standard is the 2002 Master Agreement, though some older relationships still operate under the 1992 version.2SEC.gov. ISDA 2002 Master Agreement
Because the Master Agreement is a boilerplate document, the parties negotiate a separate Schedule that tailors the standard terms. The Schedule can modify nearly anything in the Master Agreement, and where the two conflict, the Schedule controls.2SEC.gov. ISDA 2002 Master Agreement This is where the parties specify governing law, define credit support providers, and set thresholds that trigger default provisions. Negotiating the Schedule is often the most time-consuming part of setting up a new trading relationship, sometimes taking months.
Credit Support Annex
The Credit Support Annex (CSA) governs collateral. It supplements the Schedule and establishes a security interest in any collateral one party posts to the other. The CSA defines what counts as eligible collateral, sets minimum transfer amounts, specifies valuation dates, and spells out when collateral must be delivered or returned.3SEC.gov. Credit Support Annex to the Schedule to the ISDA Master Agreement For uncleared swaps, this is where margin mechanics actually live. Without a CSA, there is no agreed framework for calling collateral when the mark-to-market moves against one side.
Trade Confirmation
Each individual swap gets its own confirmation document that records the specific economics: notional amount, fixed rate, floating benchmark, payment dates, day count convention, and calculation agent. The confirmation links back to the Master Agreement and Schedule, so the broader legal terms don’t need to be renegotiated for every new trade.2SEC.gov. ISDA 2002 Master Agreement The calculation agent, typically the dealer, computes the payment amounts on each reset date.
Day Count Conventions
One detail that trips up newcomers: interest calculations depend on the day count convention specified in the confirmation. The two most common are 30/360 and Actual/360. Under 30/360, every month is treated as having exactly 30 days and the year as having 360, which simplifies the math. Under Actual/360, the numerator uses the real number of calendar days in the period, but the denominator stays at 360, so a full calendar year actually produces slightly more than one year of interest. The convention directly affects the dollar amount of each payment. Fixed legs of interest rate swaps commonly use 30/360, while floating legs tied to SOFR typically use Actual/360.
How Payments Are Calculated and Netted
In theory, both parties owe each other a payment on every settlement date. In practice, only one payment moves. The side that owes more sends the difference. This is the single most important operational feature of the swap market. It dramatically reduces the amount of cash flowing between counterparties and, with it, the risk that a payment fails.
Here is the math on a simple example. Suppose a swap has a $10 million notional, a fixed rate of 4%, and a SOFR-based floating rate that resets at 5% for a given period. The fixed-rate payer owes $400,000 annually; the floating-rate payer owes $500,000. Under netting, the floating-rate payer sends $100,000 to the fixed-rate payer. That is the only cash that moves.
Netting also matters if one side defaults. Under the ISDA Master Agreement’s close-out netting provisions, all outstanding trades between the two parties are terminated, valued, and collapsed into a single net amount owed by one party to the other.4International Swaps and Derivatives Association, Inc. The Legal Enforceability of Close-Out Netting Provisions Without enforceable close-out netting, a defaulting party’s bankruptcy trustee could cherry-pick profitable trades to keep while repudiating unprofitable ones.
Collateral and Margin While the Swap Is Live
Whether a swap is cleared or uncleared, both sides post collateral to protect against default. Two types of margin serve different purposes.
Initial margin is posted upfront as a buffer against potential future losses if one side defaults and the position has to be closed out. For interest rate swaps, the standardized schedule runs from 1% of notional for contracts under two years up to 4% for contracts over five years. For equity, commodity, and credit swaps, the percentages are significantly higher, reaching 10% to 15% of notional.5Bank for International Settlements. Margin Requirements for Non-Centrally Cleared Derivatives For uncleared swaps, initial margin requirements apply when an entity and its affiliates have an average aggregate notional amount of uncleared derivatives exceeding $8 billion, measured annually.6Federal Register. Margin Requirements for Uncleared Swaps for Swap Dealers and Major Swap Participants
Variation margin is the daily cash settlement that keeps the swap fully collateralized as market values shift. If rates move against you overnight, you receive a margin call the next morning. Covered entities trading uncleared derivatives must exchange the full amount of variation margin daily, with no minimum threshold.5Bank for International Settlements. Margin Requirements for Non-Centrally Cleared Derivatives For cleared swaps, the central counterparty handles it by marking positions to market at the end of each business day and moving cash between clearing members.
This daily cycle continues until the swap terminates, at which point collateral is returned and the final payment settles.
Where Swaps Are Executed and Cleared
Swap execution changed after the Dodd-Frank Act. Swaps subject to mandatory clearing must be executed on a swap execution facility (SEF) or a designated contract market, not just arranged over the phone.7Office of the Law Revision Counsel. 7 USC 2 – Jurisdiction of Commission SEFs must offer either an order book or a request-for-quote system running alongside an order book.8eCFR. 17 CFR Part 37 – Swap Execution Facilities Swaps that are not subject to the clearing mandate can still trade on a SEF but can also use any other method the facility offers.
Once executed, a cleared trade is submitted to a central counterparty (CCP). The CCP steps between the two original parties, becoming the buyer to every seller and the seller to every buyer. Neither original counterparty has to worry about the other’s creditworthiness; both face the CCP, which manages default risk through margin requirements and a pooled default fund.
The CFTC currently requires mandatory clearing for several classes of interest rate swaps, including fixed-to-floating swaps, basis swaps, forward rate agreements, and overnight index swaps.9eCFR. 17 CFR 50.4 – Classes of Swaps Required to Be Cleared Certain credit default swap indices are also subject to the mandate. Swaps that fall outside these categories, or that qualify for the end-user exception, can remain uncleared, though they face their own margin rules.
Ending a Swap Early
A swap doesn’t have to run to maturity. Either party can trigger early termination if the other defaults, and certain non-default events like regulatory changes or illegality can also end the contract early. When that happens, the remaining value of the deal has to be settled in cash, and the amount can be substantial.
The ISDA Master Agreement uses a “close-out amount” calculation. The non-defaulting party estimates the cost of replacing the economic terms of the deal under current market conditions, acting in good faith using commercially reasonable procedures.2SEC.gov. ISDA 2002 Master Agreement That replacement cost is combined with any unpaid amounts already owed to produce a single early termination payment.
If you are on the losing side of a terminated swap, the breakage cost is essentially the present value of all the future payments you would have received, minus the ones you would have owed. In a rising-rate environment, a fixed-rate payer sitting on an in-the-money position could receive a large termination payment. In a falling-rate environment, that same party could owe one. Early termination is not a free exit. It crystallizes whatever gain or loss the market has created since inception.
A Tax Note Worth Flagging
Most common swaps do not qualify for the favorable 60/40 capital gains treatment that applies to Section 1256 contracts like regulated futures. Federal tax law explicitly excludes interest rate swaps, currency swaps, basis swaps, commodity swaps, equity swaps, equity index swaps, credit default swaps, and similar agreements from Section 1256.10Office of the Law Revision Counsel. 26 USC 1256 – Section 1256 Contracts Marked to Market
Instead, gains and losses on most swap contracts are treated as ordinary income or loss, reported for the year the payment is received or accrued. Timing and character can get complicated when a swap is part of a hedging transaction or straddle, so the treatment depends heavily on context. The general rule is straightforward. The exceptions pile up quickly.