A cap agreement is a contract that puts a ceiling on the interest rate a borrower pays on floating-rate debt. The borrower pays an upfront premium to a counterparty, usually a bank, and in exchange the counterparty pays the borrower whenever an agreed benchmark rate climbs above a set strike rate. The loan itself stays floating, so the borrower keeps the benefit of lower rates but is protected against higher ones.
What a Cap Agreement Does
At its core, a cap is a contract between two parties. The buyer, typically a borrower, purchases protection against rising rates. The seller, typically a financial institution, agrees to compensate the buyer whenever a specified benchmark rate climbs above a level called the strike rate or cap rate. The underlying loan continues to pay a floating rate, and the cap payments offset any interest cost above the strike.
The benchmark rate used in most cap agreements today is the Secured Overnight Financing Rate, or SOFR, which the Federal Reserve Bank of New York publishes daily based on the cost of overnight borrowing collateralized by Treasury securities.1Federal Reserve Bank of New York. Secured Overnight Financing Rate Many contracts reference Term SOFR, a forward-looking rate published by CME Group in one-, three-, six-, and twelve-month tenors, because it gives borrowers a known rate at the start of each interest period.2CME Group. CME Term SOFR
Technically, a cap is not one option. It is a series of individual options called caplets, each covering one reset period. A three-year cap with quarterly resets contains twelve caplets. Each caplet settles independently, so a cap can produce payments in some periods and none in others depending on where the benchmark rate lands relative to the strike.
The Three Numbers That Define a Cap
Three variables set the economics of every cap:
- Notional principal. The dollar amount used to calculate any payments. It usually mirrors the outstanding balance of the borrower’s loan, though no principal actually changes hands between the parties. For amortizing loans, the notional can be scheduled to decline in step so the borrower isn’t paying for protection on principal that no longer exists.
- Cap rate. The interest rate threshold that triggers a payment. If the benchmark stays at or below the strike, the seller owes nothing. If it exceeds the strike, the seller pays the difference. A lower strike buys more protection at a higher premium.
- Premium. The one-time upfront fee the buyer pays. It is non-refundable, whether or not the cap ever pays out.3Fannie Mae. Multifamily Interest Rate Cap FAQs
An actual cap agreement filed with the SEC shows how those numbers look in practice: a $20 million notional, a 3.00% cap rate, and a $489,000 upfront premium.4U.S. Securities and Exchange Commission. Interest Rate Cap Agreement – Bear Stearns Financial Products Inc Combined with the benchmark rate and the payment frequency, those three figures fully define the deal.
How Payments Are Calculated
On each reset date named in the contract, the current benchmark rate is compared with the strike. If the benchmark is at or below the strike, nothing happens for that period. If it exceeds the strike, the cap is in the money and the seller owes the difference between the two rates, multiplied by the notional and adjusted for the length of the period.3Fannie Mae. Multifamily Interest Rate Cap FAQs
A short example. Take a $10 million notional, a 4.00% cap rate, a benchmark reading of 5.50% on a reset date, and a quarter of roughly 90 days. The payment works out to (5.50% − 4.00%) × $10,000,000 × (90/360), or $37,500. That payment offsets the borrower’s higher interest cost on the underlying loan, so the borrower’s effective rate for the period stays at 4.00% plus whatever spread the loan carries.
Settlement frequency varies. Fannie Mae multifamily caps settle monthly; many other commercial caps settle quarterly. The Confirmation document names the exact schedule.
What Determines the Premium
Cap premiums aren’t arbitrary. Five factors set the price:
- Strike rate versus current benchmark. The closer the strike sits to the current market rate, the more likely the cap pays out and the more expensive it is. Setting the strike well above today’s rate is cheap, but only protects against extreme moves.
- Term. Longer-dated caps cost more because there are more reset periods where the benchmark could exceed the strike. A five-year cap is substantially more expensive than a two-year cap at the same strike.
- Notional amount. Premium scales roughly in proportion. Double the notional, roughly double the premium.
- Forward rate curve. When the market expects rates to rise, premiums increase because payouts become more likely. When the curve slopes down, caps get cheaper.
- Implied volatility. This measures market uncertainty about the future path of rates. Higher uncertainty raises the chance of large moves and lifts premiums even if the forward curve hasn’t shifted much.
Each caplet is priced individually using an options pricing framework, and the total premium is the sum of the caplet values. That is why a cap with monthly resets tends to cost more than the same term and strike with quarterly resets: it contains more individual options.
Caps Compared to Swaps, Floors, and Collars
Borrowers hedging floating-rate debt usually weigh a cap against an interest rate swap. The two serve different purposes. A swap converts the floating rate to a fixed rate outright. There is no upfront premium, but the borrower gives up all benefit of falling rates and can face a significant mark-to-market liability if the swap has to be unwound early. A cap keeps the downside benefit when rates drop, in exchange for an upfront premium.
The practical difference shows up at exit. Caps carry no prepayment penalty and can be terminated early, often at no cost to the buyer beyond forfeiting any remaining time value. Swaps can become large liabilities over time and are credit-intensive, so lenders scrutinize the borrower’s financial strength more closely. For transitional assets where the borrower expects to sell or refinance in a few years, caps are the more common choice.
An interest rate floor works in the opposite direction from a cap. The seller pays the buyer whenever the benchmark falls below a specified floor rate. Floors are typically used by lenders or investors who want a guaranteed minimum return on floating-rate assets.
A collar combines the two. The borrower buys a cap and sells a floor at the same time. Premium collected from selling the floor offsets part or all of the cost of buying the cap. In a zero-cost collar, the two premiums cancel. The trade-off is real: selling the floor means giving up the benefit of rates dropping below the floor level. The borrower’s effective interest expense is confined to a band between the floor and the cap.
When a Lender Requires a Cap
Borrowers don’t always purchase caps voluntarily. Many lenders, particularly in commercial real estate, require an interest rate cap as a condition of a floating-rate loan. The reasoning is straightforward: the lender wants assurance that rising rates won’t push debt service above what the property’s income can support.
Fannie Mae’s multifamily program shows how prescriptive these rules can be. A borrower taking out a Structured Adjustable Rate Mortgage must purchase a third-party interest rate cap and keep it in place until the loan matures or converts to fixed. The cap must come from a Fannie Mae-approved provider, the minimum term is five years, and if the cap expires before the loan does, the borrower must buy a replacement. Fannie Mae also requires the borrower to fund a cash reserve equal to at least 110% of the current replacement cap cost.5Fannie Mae Multifamily Guide. Interest Rate Caps
For borrowers subject to rules like these, the cap premium and the reserve behind it are required closing costs, not optional ones.
Exiting a Cap Early
Unlike swaps, caps are generally borrower-friendly on the way out. Because the buyer has already paid the full premium and has no ongoing obligations, terminating a cap early usually carries no breakage cost or prepayment penalty. If time value remains, the borrower may be able to sell the cap back to the counterparty at its current market value. Walking away is also an option, since the buyer’s only exposure was the original premium.
That flexibility is one of the main reasons caps are favored for shorter-term transitional loans. The borrower isn’t locked into a position that could produce a termination payment owed to the counterparty.
The Documentation Behind a Cap
Cap agreements are documented under a standardized framework published by the International Swaps and Derivatives Association (ISDA), built from three pieces.
The ISDA Master Agreement is the foundational contract between the two counterparties. It sets the general legal terms that apply to every transaction between them: default provisions, termination rights, governing law, dispute resolution. The current standard form is the 2002 ISDA Master Agreement, and most institutional counterparties already have one in place before executing any specific deal.6U.S. Securities and Exchange Commission. ISDA 2002 Master Agreement The accompanying Schedule is where the parties customize those standard terms; when the Schedule conflicts with the Master Agreement, the Schedule controls.
The Confirmation is the deal-specific document. It locks in the notional, cap rate, premium, benchmark, payment dates, and maturity. Each new cap between the same counterparties gets its own Confirmation, while the Master Agreement and Schedule remain in place.4U.S. Securities and Exchange Commission. Interest Rate Cap Agreement – Bear Stearns Financial Products Inc Confirmations incorporate ISDA’s standardized definitions by reference; the current standard is the 2021 ISDA Interest Rate Derivatives Definitions, which replaced the 2006 Definitions.7ISDA. 2021 ISDA Interest Rate Derivatives Definitions
A Credit Support Annex (CSA) can govern collateral between the counterparties, specifying acceptable collateral types, thresholds, and haircuts. CSAs are more commonly associated with swaps than with caps, because the cap buyer pays the premium upfront and has no ongoing payment obligations. When a cap sits inside a larger derivatives portfolio between two counterparties, the CSA applies across all of it.
Modern cap documentation also includes fallback provisions that specify what happens if the benchmark rate is discontinued. After the LIBOR transition, ISDA published the 2020 IBOR Fallbacks Protocol, and the 2021 Definitions now build fallback mechanics directly into new contracts. If the benchmark referenced in a cap ceases publication, the contract transitions to a replacement rate rather than becoming unworkable.
Counterparty Credit Risk
Counterparty risk is the possibility that the seller can’t make payments when they’re owed. It matters because the cap’s value to the borrower depends entirely on the seller’s ability to perform, precisely during the market conditions (sharply rising rates) when the seller faces its largest obligations.
Because the buyer pays the premium upfront and has no future obligations, the credit exposure runs in only one direction. The seller may owe substantial payments over the life of the cap; the buyer owes nothing further. That asymmetry is why the choice of counterparty is one of the most consequential parts of the transaction.
Borrowers manage this risk in a few ways. Lender-imposed cap requirements often specify minimum credit ratings for acceptable providers, and Fannie Mae requires borrowers to buy caps only from its list of approved providers.5Fannie Mae Multifamily Guide. Interest Rate Caps For borrowers not bound by specific lender rules, picking a well-capitalized, highly rated counterparty is the primary defense. The ISDA framework helps as well: events-of-default provisions allow early termination if a counterparty’s creditworthiness deteriorates, and a CSA can require collateral to reduce unsecured exposure.