What it means
Every floating rate has two parts. The reference rate is a published market benchmark that reflects the general cost of money, and the margin, sometimes called the spread, is a fixed addition set by the lender to reflect the borrower's credit quality and the security offered.
A strong borrower might pay the reference rate plus 1.5%, while a weaker one pays the same reference rate plus 4%. The reference rate resets on a defined schedule, commonly monthly, quarterly or semi-annually, and the new payment applies until the following reset.
This is why floating rate borrowers should model their cash flow at several different rate levels rather than at today's rate alone. A business that can only just afford its payments at the current rate has effectively bet the company on monetary policy.
Lenders like floating rates because they remove interest rate risk from their own books, passing it to the borrower. This is also why the starting rate is normally lower than the fixed alternative: the borrower is being paid a small discount for carrying the uncertainty.
Most working capital facilities, overdrafts and revolving credit lines are floating by default, since they are short term and repriced constantly anyway. Several tools exist to limit the downside.
An interest rate cap sets a maximum rate for a fee, a collar sets both a maximum and a minimum, and an interest rate swap exchanges floating payments for fixed ones with a counterparty. Larger borrowers routinely combine a floating loan with a swap, which gives them a floating facility that behaves like a fixed one.
The nuance worth remembering is that floating rates are not automatically riskier in every context. A business whose revenue naturally rises when interest rates rise, such as one holding large cash balances or selling into an inflation-linked market, may find floating debt a better match for its income.
The right choice depends on how the borrowing behaves relative to the rest of the business, not on a forecast of where rates will go.
In practice
Real-world examples
Example 1
A retailer draws on a $1,500,000 revolving credit facility priced at reference plus 2.5%. Because the facility is repaid and redrawn seasonally, the floating structure suits the business, and the finance team simply models interest at three different rate scenarios in the annual budget.
Example 2
A property investor with $8,000,000 of floating rate debt buys an interest rate cap at 7% for a three-year term. The premium costs $95,000 upfront, which the investor treats as insurance protecting the rental yield rather than as a bet on rates.
Example 3
A mid-sized manufacturer borrows floating because its bank will not offer fixed beyond three years, then enters a seven-year interest rate swap with the same bank. The combination gives it a known effective rate for the full term of the underlying loan.
Think of it
A floating interest rate is like riding a tandem bicycle where the terrain dictates your pedalling speed. When you hit a downhill slope, pedalling gets easier and faster. When you face a steep uphill climb, the resistance increases and the ride demands much more effort.
Formula
Calculation
Floating Rate = Reference Rate + Margin
Annual Interest = Principal x Floating Rate
Worked example. A wholesaler holds a $600,000 term loan priced at the central bank reference rate plus a margin of 2.0%. At the start of the year the reference rate is 4.5%.
Floating rate = 4.5% + 2.0% = 6.5%.
Annual interest = $600,000 x 6.5% = $39,000.
Over the following eighteen months the reference rate climbs to 6.5%.
New floating rate = 6.5% + 2.0% = 8.5%.
New annual interest = $600,000 x 8.5% = $51,000.
The interest cost rises by $51,000 - $39,000 = $12,000 a year, which is roughly 31% more than the original figure, even though the principal has not changed at all.
Suppose the wholesaler had bought an interest rate cap fixing the maximum payable rate at 8.0%. Interest would then be capped at $600,000 x 8.0% = $48,000, saving $3,000 a year against the uncapped position, in exchange for the upfront premium paid for the cap.Case study
Seen in the real world
Here is an illustrative example involving a fictional company. Larkspur Care Homes operated six residences funded with $14,000,000 of floating rate debt at reference plus 2.2%, chosen because it was 0.9 percentage points cheaper than the fixed quote when the facility was arranged. Roughly 70% of its revenue came from local authority placements with fees set annually and adjusted only for inflation.
Over two years the reference rate rose by three percentage points, adding around $420,000 a year to interest costs. Because fee income was contractually fixed for the year and staffing costs were also rising, the extra interest came straight out of an operating margin that had been about 9%. Covenant headroom on interest cover disappeared within three quarters.
Larkspur negotiated a standstill with its lender and then swapped $10,000,000 of the debt to a fixed rate, leaving $4,000,000 floating for flexibility. In this fictional case management concluded that the original decision had been made on the day one price difference alone, without asking whether revenue could ever move to match the cost.
Watch out
Common mistakes
- Comparing fixed and floating options only on the starting rate. The floating rate is lower at the outset by design, and the real comparison is against a realistic range of future rates across the whole term.
- Assuming the margin will change with market conditions. The reference rate moves but the margin is contractually fixed for the term, so a borrower whose credit improves will not automatically see a lower spread without renegotiating.
- Budgeting at the current rate only. Floating rate borrowers should stress test their cash flow at two or three percentage points above today's rate, because the payment can change with only a few weeks of notice.
Questions
People also ask
What are floating rates usually linked to?
Published market benchmarks such as central bank policy rates, prime lending rates or interbank reference rates, with the exact index named in the loan agreement.
Can a floating rate loan be converted to fixed?
Often yes, either by refinancing, by exercising a switch option written into the facility, or by entering an interest rate swap that converts the economics without changing the loan itself.
How often does the rate actually change?
It changes at the reset dates in the agreement, which are commonly monthly or quarterly, so an increase announced today may not hit the payment until the next reset.