What it means
Normally, when you borrow money and make a repayment, part of that payment covers the interest for the period, and the remainder pays down the actual loan amount, known as the principal. With negative amortisation, your monthly payment is set lower than the interest that accumulates.
This often happens with certain types of mortgages or flexible business loans designed to keep initial payments artificially low. While it gives you immediate breathing room on your cash flow, it comes with a hidden cost.
Because the unpaid interest rolls over into the principal, you end up paying interest on top of interest. Over time, this creates a snowball effect where your overall debt increases even though you are making regular payments.
Eventually, the loan terms will force a recalculation, leading to a sharp payment shock when you are required to pay off the much larger balance.
In practice
Real-world examples.
Example
A startup founder takes a flexible business loan with payments below the monthly interest. A 100,000 pound loan grows to 105,000 pounds after a year because unpaid interest keeps adding to the balance.
Example
A retail SME uses a special financing package with low introductory instalments. After 24 months of negative amortisation, their initial 50,000 pound debt has ballooned to 54,000 pounds, raising future costs.
Example
A commercial property investor buys a warehouse using a deferred interest facility. Their low monthly payments fail to cover interest charges, increasing their total mortgage from 200,000 to 215,000 pounds.
Think of it
“Imagine riding a stationary exercise bike where the resistance automatically increases faster than you pedal. Even though you are moving your legs, you are actually losing ground and slipping backwards.
Formula
Calculation
Ending Balance = Beginning Balance + Interest Charged - Payment Made
Example: If you owe 100,000 pounds at 6 percent annual interest, the monthly interest is 500 pounds. If your payment is only 300 pounds, the math is:
100,000 + 500 - 300 = 100,200 pounds new balance.Case study
Seen in the real world.
GreenLeaf Logistics, a mid-sized delivery firm, needed new vans to expand operations. To preserve short-term cash flow during a slow season, the directors opted for a specialist vehicle loan that offered low introductory payments featuring negative amortisation. For the first eighteen months, their monthly payments were fixed at 400 pounds, while the actual interest accumulating on the 80,000 pound loan was 600 pounds each month. The 200 pound difference was added directly to their loan principal every month.
By month nineteen, the total debt had grown from 80,000 pounds to 83,600 pounds. At this point, the loan agreement triggered a mandatory recalculation, resetting the monthly payments to amortise the newly inflated balance over the remaining term. GreenLeaf suddenly faced monthly payments of 950 pounds instead of the expected 400 pounds. The sudden jump strained their operating budget, forcing them to delay office upgrades and tighten expenses to avoid defaulting on the restructured debt.
Watch out
Common mistakes.
- Assuming that making every scheduled payment means you are successfully paying off your debt.
- Ignoring the loan contract details regarding the date when payments will automatically reset to a higher amount.
- Failing to calculate the long-term total cost of the borrowing, focusing only on the short-term cash flow relief.
Questions
People also ask.
Why would anyone choose a loan with negative amortisation?
It provides short-term cash flow relief for businesses or individuals who expect their income to rise significantly in the future.
Is negative amortisation legal?
Yes, but lenders are heavily regulated and must clearly disclose the risks and the point at which payments will increase.
What is a recast?
A recast is when the lender recalculates your monthly payments to ensure the loan is fully paid off by the end of its original term, usually causing payments to jump.
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