Interest Rate Caps on Floating-Rate Apartment Loans
An interest rate cap is a contract a borrower buys that pays out when a floating interest rate rises above a chosen level. On a floating-rate apartment loan, the cap limits how much a rise in the benchmark rate can add to your interest cost, but only up to a point and only for the life of the cap. If you are a sponsor, DoorRaise helps you raise the equity for the deal, and the rate cap is one of the costs in your budget. If you are an investor, the cap tells you how much rate risk the deal has covered and for how long.
This post is part of our guide to real estate syndication. It explains floating rates, how a cap works, what happens when it expires, and what to ask. Rules are as of October 2026.
What is a floating-rate loan?
A floating-rate loan has an interest rate that resets on a schedule, usually monthly. The rate is a benchmark plus a spread. The spread is fixed in the loan documents. The benchmark moves.
In the United States, many floating-rate commercial loans now use the Secured Overnight Financing Rate, called SOFR, published by the Federal Reserve Bank of New York. See the New York Fed's SOFR page for what it measures and its current published value. Check the current benchmark and the loan's exact terms yourself, because benchmarks and market conventions change.
Bridge loans are the usual floating-rate loans in apartment syndications, because they fit buildings that are being renovated. Our bridge loan vs. agency loan post compares them with fixed-rate agency loans. A fixed-rate loan keeps the rate the same for its term, so it has no cap and no benchmark risk during that term, though other risks remain.
What is an interest rate cap?
A cap is a contract with a bank or dealer, called the counterparty. It has a few terms:
- Index. The benchmark it follows, such as SOFR.
- Strike rate. The level the index must rise above for the cap to pay.
- Notional amount. The loan balance the cap covers. It is often the full loan amount.
- Term. How long the cap lasts, in months.
- Premium. The one-time price paid to buy it.
If the index stays below the strike, the cap pays nothing and the borrower pays whatever the loan charges. If the index rises above the strike, the counterparty pays the borrower the difference on the notional amount, which offsets the extra interest.
So the borrower's benchmark cost is limited to the strike rate for the term of the cap. The spread still applies on top.
A hypothetical example
This example is hypothetical, for illustration only. The numbers are round and are not a forecast, and they do not reflect current rates.
Suppose a loan of $4,000,000, interest only, pays the benchmark plus a 3.00% spread, and the sponsor buys a cap with a 4.00% strike. The building's net operating income (NOI) is $350,000.
| Case | Benchmark | Rate paid by the borrower | Annual interest | NOI / interest |
|---|---|---|---|---|
| Benchmark at 4% | 4.0% | 7.0% | $280,000 | 1.25x |
| Benchmark at 6%, no cap | 6.0% | 9.0% | $360,000 | 0.97x |
| Benchmark at 6%, with cap | 6.0% (cap pays 2%) | 7.0% | $280,000 | 1.25x |
Without a cap, a 2-point rise in the benchmark adds $80,000 of interest and pushes NOI below the interest cost. With the cap, the cost stays at the strike level plus the spread, so the building keeps covering its loan payment. The cap's premium is the price of that protection, and it is a cost of the deal.
The ratio in the last column is a debt service coverage ratio, covered in our underwriting basics. Lenders set a minimum, so a rate rise can cause a loan problem, not just a smaller distribution.
Who buys the cap and why?
Many floating-rate lenders require the borrower to buy a cap, and some specify the strike rate and the minimum term. The lender wants to know the borrower can keep paying if rates rise. The borrower pays the premium at or before closing, so it is a line in the budget. See sources and uses.
Some lenders accept a cap bought from an approved provider only, and some require the borrower to assign it to the lender as collateral. The loan documents spell this out. A higher strike usually means a lower premium and less protection, and a lower strike means a higher premium and more protection, so the choice trades cost against risk.
What happens when the cap expires?
A cap is not permanent. When the term ends, the protection ends. If the loan is still outstanding, the borrower generally has to buy a new cap to keep the loan in good standing, and the price depends on rates and market conditions at that time. If the rate environment has moved, the new cap can cost far more than the first one, or the lender may ask for a different strike.
That is why the cap term, the loan term and the business plan need to line up. Ask:
- When does the cap expire, and when does the loan mature?
- Does the loan have extension options, and what must be true to use them? Lenders often require a cap for each extension and a minimum level of debt coverage.
- How much is set aside for extension costs, and is it funded from the raise or from cash flow?
- What is the plan if the building cannot cover the new cap, an extension fee and the loan payment?
A shortfall may require a capital call, a paused distribution or a sale. See what happens if a syndication loses money for how those play out. A refinance into a fixed-rate loan can end the exposure, but it is not guaranteed, and our cash-out refinance guide explains why.
How does rate risk show up in underwriting?
It shows up in debt service, which shows up in coverage and in distributions. Debt service on a floating-rate loan changes with the benchmark. A good model shows more than one rate path:
- A base case from the current forward expectations stated in the model, with its source named.
- A higher-rate case, which shows when the cap pays and what coverage looks like.
- A case where the cap has expired and the benchmark is at a higher level, to see whether the extension and the loan work.
Do not rely on a forecast of where rates will go. Nobody knows, and a model that depends on one is a weak model. Ask for stress cases instead, as described in our financial projections guide, and test your own with the cap rate and DSCR calculator.
If a plan to renovate and raise rents is also behind schedule, rate risk and execution risk arrive together. The value-add business plan explains why plans slip.
What about a fixed-rate loan?
A fixed-rate loan has no benchmark exposure during its term, so it needs no cap. The trade-offs are different: fixed-rate loans can limit when you can sell or refinance without a prepayment cost, and they may be unavailable for a building that is not yet stable. Neither type is better in every case. Compare the specific terms, including prepayment costs.
Our take
Our view is that a floating-rate loan with no cap, or with a cap that ends before the business plan does, is a serious red flag. When you read a deal, find the cap's strike, cost, expiration and the extension budget in the same place you find the purchase price. If they are not in the documents, ask.
How DoorRaise fits in
DoorRaise helps sponsors raise equity for apartment buildings with 5 or more units under Rule 506(b) or 506(c). It prepares the offering documents from the sponsor's inputs, coordinates escrow with an independent escrow agent named on the deal page, and handles filings. It does not arrange loans or rate caps. The sponsor works with a lender or broker, and then describes the loan terms and risk to investors.
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DoorRaise is built for apartment buildings with 5 or more units: one link for the deal, escrow until closing and a standard fee card.
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FAQ
What is an interest rate cap on a loan?
A contract that pays the borrower when a floating-rate benchmark goes above an agreed strike rate. It limits the benchmark part of the interest cost for the cap's term.
Does a rate cap fix my interest rate?
No. It limits how high the benchmark part of your rate can go. If rates fall, your cost falls too. The loan's spread is added on top either way.
Who pays for the rate cap?
The borrower, usually at closing. In a syndication that means the deal's company pays it from the money raised, so it should be in the budget and the offering documents.
What happens if the cap expires before the loan is repaid?
The borrower typically has to buy a new cap or meet other lender conditions. The price depends on market conditions then, and the lender may require it as a condition of an extension.
Is a floating-rate loan riskier than a fixed-rate loan?
It has benchmark risk that a fixed-rate loan does not during its term, and it can reset higher. A cap reduces the risk without removing it. Fixed-rate loans have their own constraints.
What should an investor ask about the rate cap?
The strike rate, the expiration, the cost to extend, the reserve for it, and what the model shows if the benchmark rises above the strike.
Sources
- Federal Reserve Bank of New York, Secured Overnight Financing Rate (SOFR)
- Fannie Mae, Multifamily fixed-rate mortgage loans
- Investor.gov, Investor Bulletin: Publicly Traded REITs
This article is general information, not legal, tax or investment advice. Talk to a securities attorney and a CPA about your deal. DoorRaise is not a law firm, broker-dealer, investment adviser or funding portal.