Floating interest rates on business loans: calculation and risks
An offer of “key rate + 5 percentage points” does not fix costs for the full loan term. The final rate depends on the benchmark and contractual terms. We show how to calculate interest, compare offers and check whether the business can withstand a higher cost of borrowing.
What to check before signing
- Formula: which benchmark the bank uses and the margin it adds.
- Reset date: when a new benchmark value begins to affect your loan.
- Limits: whether there is a minimum rate or a cap on increases.
- Cash flow: whether receipts will cover interest and principal if conditions deteriorate.
Comparing only the interest rate on the disbursement date is insufficient. Calculate using the same debt amount, period and schedule, then check fees and other expenses.
How a floating loan interest rate works
In a common model, the annual interest rate consists of a benchmark plus the bank's margin. If the benchmark is the Bank of Russia key rate, the formula may be:
Loan interest rate = key rate + bank margin
With a benchmark of 14% and a margin of 5 percentage points, the result is 19% per year. This adds percentage points; it is not a 5% increase in 14%.
If the benchmark rises to 17%, the same margin produces a calculated rate of 22% per year. At a benchmark of 12%, it is 17% per year. These results apply if the agreement has no other restrictions or conditions governing rate changes.
According to the Bank of Russia, as of 14 October 2026 the key rate is 14% per year. This is the value on the article's preparation date, not a forecast for the loan term. Before a new calculation, check the latest Bank of Russia data.
Why a lower benchmark may not produce the expected savings
Check whether your agreement specifies a minimum interest rate. If an applicable clause sets a minimum final rate of 20%, a formula result of 19% does not mean interest accrues at 19%: in that example, 20% is used.
The minimum may apply to the benchmark itself or to the final rate; these are different formulas. The calculator below supports only a minimum final annual rate. The specific contractual terms need to be incorporated into your calculation separately.
When a new key rate affects a loan
The date of the central bank's decision, the date the new benchmark takes effect and your loan's reset date may differ. The agreement sets the reset procedure: for example, it may link the calculation to a benchmark change or a particular date each month or quarter.
Ask the bank to show a worked example: which value applies before the benchmark changes, which applies afterwards and from what date. Check the rules for increases and decreases equally carefully.
If the rate or debt balance changes during the period, calculate interest in separate intervals. Applying the latest rate to the entire month is appropriate only when the agreement specifically requires that method.
Do not confuse accrual with payment: interest may accrue daily and be debited on a specified payment date. The amount payable depends on both the number of days and the outstanding debt balance.
Example: a 19% floating rate or a 20% fixed rate
Suppose a business compares two illustrative offers for 10 million RUB. The debt remains unchanged, and interest accrues for 31 days, from 14 October to 13 November 2026 inclusive. The example uses actual days and a 365-day year.
The first offer charges the benchmark plus 5 percentage points. The second has a fixed rate of 20% per year. This example has no minimum rate. Fees are excluded for now.
| Scenario | Annual rate | Interest for the period |
|---|---|---|
| 14% benchmark + 5 percentage point margin | 19% | 161 369.86 RUB |
| 17% benchmark + 5 percentage point margin | 22% | 186 849.32 RUB |
| Fixed-rate offer | 20% | 169 863.01 RUB |
In the base case, the floating rate saves about 8,493 RUB over this period compared with the fixed rate. If the benchmark rises by 3 percentage points, the floating-rate cost increases by approximately 25 479 RUB relative to the base calculation.
Interest = debt × rate / 100 × days / days in the year
This compares interest expenses only. The payment may also include principal repayment and contractual fees. If using a credit facility, separately check the unused revolving credit facility fee.
Business floating interest rate calculator
Compare a base rate, an illustrative increase scenario and a fixed-rate offer. The calculator works out interest on a constant debt balance. Each scenario applies throughout the selected period.
Calculation for 31 days — from 14 October 2026 to 13 November 2026 inclusive.
Increase in interest expense over the base case: 25,479.46 RUB.
The base case is 8,493.15 RUB cheaper than the fixed rate. The increase scenario is 16,986.31 RUB more expensive than the fixed rate.
The result estimates interest; it is not a repayment schedule or the total cost of the loan. Principal repayment, fees, penalties, rate increase caps and special statutory restrictions are excluded. If the debt or rate changes, split the period into intervals. The bank's rounding method may differ.
Terms to check in the loan agreement
| Term | What to clarify with the bank |
|---|---|
| Benchmark | Its exact name, source and the date of the value used in the calculation. |
| Margin | Does it remain unchanged throughout the term? Which contractual events can change it? |
| Rate reset | When do increases and decreases apply? How does the bank notify you of the new value? |
| Minimum and increase cap | Are there restrictions? Do they apply to the benchmark or to the final rate? |
| Accrual and payment | Which days are included, how are leap years treated and on what date is interest paid? |
| Early repayment | What notice is required, is there a fee and is partial repayment possible? |
| Related conditions | Do account turnover, insurance, security or covenant breaches affect the rate and costs? |
Special restrictions on floating rate increases apply to borrowers with microenterprise status. Protection depends on the agreement date, borrower status and statutory exceptions. Ask the bank to confirm the applicable rate increase limits and notification procedure. Do not automatically extend these rules to every individual entrepreneur or every SME.
If the rate depends on compliance with financial conditions, review these alongside the payment schedule. For more detail, see the article loan agreement covenants.
How to decide whether a floating rate suits your business
- Prepare a monthly forecast. Use actual dates for customer receipts, taxes, payroll, purchases and payments on all debts.
- Calculate several scenarios. Alongside the starting rate, test illustrative increases, such as 1 and 3 percentage points. Choose the scale of the test to reflect the loan term and liquidity buffer.
- Combine risks. Check what would happen if higher interest costs coincided with a delayed payment from a major customer.
- Compare offers on the same basis. Use the same debt balance, period, repayment schedule and complete list of mandatory expenses.
- Determine your cash buffer. The reserve should account for adverse-scenario payments and essential operating expenses, rather than just one month's interest.
A fixed rate makes interest expenses easier to plan within the contractual terms. A floating rate can reflect a declining benchmark but exposes the borrower to the risk of an increase. The decision depends on cash flow headroom and the terms of the specific offers.
To assess debt commitments, you can use the debt service coverage ratio (DSCR). Calculate it using the method in your agreement or an agreed financial model: there is no universal safe threshold for every business.
If principal repayments are uneven, first review the loan repayment schedule. A small rate saving does not offset a cash shortfall on the date of a large repayment.
Frequently asked questions
If the key rate falls, will the bank immediately reduce interest?
Check the contractual formula, reset date and restrictions. A lower benchmark does not necessarily apply to your loan on the same day. A minimum rate, if included in applicable terms, may also limit the reduction.
Is a floating rate always better value than a fixed rate?
No. The outcome depends on future benchmark values, the margin, restrictions, debt schedule and costs under each offer. Comparing only starting rates does not show the cost over the full term.
How much do costs rise when the rate increases by one point?
With constant debt of 10 million RUB over 31 days in a 365-day year, a 1 percentage point increase in the final rate adds approximately 8,493 RUB in interest. If a minimum or rate increase cap applies, a benchmark change may produce a different result.
Can I switch from a floating rate to a fixed rate?
This depends on the agreement and the bank's consent. Discuss amending the terms or refinancing, then account for fees, security requirements and documentation costs. A switch cannot be assumed to be guaranteed.
Does the calculator show the monthly payment?
It shows only interest for the selected days on a constant debt balance. To calculate the payment, separately include principal repayment and other contractual amounts.
When to seek help
If the bank offers several rate options, the agreement includes restrictions or the business uses several credit facilities, comparing the offers within a single financial model can help.
NG Finance can help review financing terms, assess interest expenses and prepare questions for the bank. To start, provide the loan amount, purpose, term and any existing offers.
Discuss business financing