Interest Rate Cap
An interest rate cap is a hedge that sets a ceiling on the benchmark rate, usually SOFR, that prices a floating-rate commercial real estate loan. When the benchmark rises above the strike, the cap counterparty pays the difference on the covered notional, so the borrower’s benchmark cost stops at the strike. The loan spread still sits on top, the cap carries its own upfront premium, and its protection ends on its own expiration date, which can fall before the loan matures.
How a cap turns an open-ended benchmark into a ceiling
A floating-rate loan charges the benchmark plus a fixed spread, so every move in the benchmark flows straight into debt service. A cap is a second contract that sits beside the loan. Below the strike it pays nothing, and the borrower carries the benchmark as it stands. Above the strike it pays the excess, which offsets the extra interest the loan charges.
In the single-asset, single-borrower floating-rate market, a common illustration is a 4% strike on SOFR. If SOFR climbs past 4%, the borrower’s net cost on the benchmark component stays at 4% and the counterparty funds the difference.
The ceiling applies to the benchmark only. The spread rides on top in every scenario, so the highest all-in rate the borrower can face is the strike plus the spread.
“One of the really interesting things from the SASB floating-rate market is that a borrower usually writes an interest rate cap on the underlying loan.”
Where a cap pays and where it stops
The strike fixes the benchmark level where payments begin. A strike set well above the current benchmark leaves a wide band of increases that the borrower absorbs before the cap pays a dollar.
The notional fixes the balance on which any payment is calculated. A notional below the loan balance leaves the difference floating with no ceiling at all.
The term fixes the dates between which payments can occur. A term that ends before maturity leaves the later periods open.
Because the cap is a separate contract, it is priced separately. The premium is a cash cost paid whether or not the benchmark ever reaches the strike.
Why cap protection can end before the loan does
A cap protects only while its contract runs. In a sample of CRE CLO floating-rate loans, 40% of the rate cap agreements with expiration dates in the following four years expire before their loans mature. In the same sample, current note rates on loans without a cap agreement averaged about 200 bps above the effective note rates on capped loans.
Floating-rate CRE CLO loans require caps for the initial three-year term. Each one-year extension option can bring higher hedging costs for the borrower.
When a cap lapses with the loan still outstanding, benchmark increases reach debt service with no offset. That pressures debt service coverage and creates refinancing risk at maturity.
The cost of replacing a cap at extension or refinance
Floating-rate multifamily borrowers may have to reset interest rate hedges at costly premiums to extend maturing loans. Rising rates can also reduce refinancing proceeds, which may require new capital.
In some practitioners’ experience, replacement caps on maturing high-octane debt can cost 10 or 20 times what borrowers first paid.
The replacement premium is a fresh cash outlay on the day the new cap is bought, and it sits in the plan next to every other cost of extending.
Debt service stress when the benchmark is allowed to float
The pressure shows up in coverage tests. In the single-asset floating-rate CMBS market, 20% of loans could not meet their debt service coverage ratio if SOFR were allowed to move to 4.8%.
Property type adds a second layer. Many office floating-rate loans pair deteriorating asset fundamentals with a high debt service burden, and that burden becomes heavier when caps expire. The hedge props up cash flow that may already be under strain from the asset side.
Worked example: a hypothetical $20 million floating-rate loan with a 4 percent strike
A hypothetical interest-only loan of $20,000,000 is priced at the benchmark plus a 3% spread. The borrower buys a one-year cap with a 4% strike on a $20,000,000 notional for a premium of $150,000. Property net operating income is $2,520,000. Both cases cover the same year, the same balance and the same premium.
Base case, benchmark at 3%. The all-in rate is 3% plus 3%, or 6%. Interest is $20,000,000 multiplied by 6%, or $1,200,000. The benchmark sits below the strike, so the cap pays nothing. With the $150,000 premium, total cost is $1,200,000 plus $150,000, or $1,350,000.
Stressed case, benchmark at 6%. The uncapped all-in rate is 6% plus 3%, or 9%, and interest is $20,000,000 multiplied by 9%, or $1,800,000. The benchmark exceeds the strike by 6% minus 4%, or 2%. The cap pays $20,000,000 multiplied by 2%, or $400,000. Net interest is $1,800,000 minus $400,000, or $1,400,000, which matches an effective all-in rate of 4% plus 3%, or 7%. With the $150,000 premium, total cost is $1,400,000 plus $150,000, or $1,550,000.
Against the same stressed year with no cap, the capped borrower pays $1,800,000 minus $1,550,000, or $250,000 less after the premium. Coverage on interest moves the same way: $2,520,000 divided by $1,800,000 is 1.4x uncapped, and $2,520,000 divided by $1,400,000 is 1.8x with the cap paying. In the base case the $150,000 premium bought nothing that year, which is the price of holding the ceiling.
Mistakes that distort the reading of a cap
Treating the strike as a ceiling on the all-in rate is an arithmetic slip. The strike caps only the benchmark. In the example, a 4% strike and a 3% spread produce a 7% worst-case rate, so reading the ceiling as 4% understates the cost by the full spread.
Matching the cap to the initial term and ignoring extension options leaves later years open. A three-year cap on a loan with two one-year extensions leaves two years of exposure, priced at whatever the market charges when each option is exercised.
Comparing capped and uncapped loan costs without the premium flatters the capped loan. In the base case above, the capped borrower spends $150,000 more than the uncapped borrower, because the premium is paid and nothing comes back when the benchmark stays under the strike.
Reading the cap as protection for the whole balance when the notional is smaller leaves part of the loan exposed. Interest on the uncovered portion floats freely, so a cap on half the balance offsets half the increase.
Underwriting coverage only at the current benchmark hides the tests that matter. Coverage at the strike and coverage after expiry show whether the loan carries through a rate path.
Questions to ask about a cap before relying on it
Which benchmark does the cap reference? The strike works only when read against the same rate that drives the loan’s interest.
What is the strike, and where does the all-in rate stop? The ceiling equals the strike plus the spread.
What notional does the cap cover? Any balance above the notional floats without a ceiling.
When does the cap expire relative to maturity and each extension option? Every uncovered period needs a replacement hedge.
What would a replacement cap cost at extension? Pricing on that day depends on the benchmark then, and reset premiums can run many times the original.
Does the extension budget carry the premium? A reset cost left out of the plan becomes a new capital need.
What is debt service coverage at the strike and after expiry? Those two figures show how much room the loan has.
How does the asset’s cash flow trend against the hedge term? Weaker fundamentals combined with an expired cap squeeze coverage from both sides.