Negative amortization occurs when a permitted payment is below accrued interest, causing unpaid interest to be added to principal.
Negative amortization occurs when a loan payment is less than the interest accrued for the period and the unpaid interest is added to principal. The borrower can make the permitted payment on time while the amount owed still increases.
The defining fact is balance growth caused by unpaid interest. A low payment, payment deferral, or interest-only period is not automatically negative amortization; compare the required payment with accrued interest and check whether any shortfall is capitalized.
Ignoring fees, advances, and separate principal payments, the balance update is:
Ending balance = opening balance + accrued interest - payment
If the payment exceeds accrued interest, principal declines. If payment equals accrued interest, principal stays level. If payment is less than accrued interest, principal increases by the shortfall.
Assume a loan has:
Interest is:
$100,000 x 0.50% = $500.00
The $350 payment leaves $150.00 unpaid. The new balance is:
$100,000 + $500 - $350 = $100,150.00
Interest is now calculated on the larger balance:
$100,150 x 0.50% = $500.75
The $350 payment leaves $150.75 unpaid. The new balance is:
$100,150 + $500.75 - $350 = $100,300.75
| Month | Opening balance | Interest | Payment | Capitalized shortfall | Ending balance |
|---|---|---|---|---|---|
| 1 | $100,000.00 | $500.00 | $350.00 | $150.00 | $100,150.00 |
| 2 | $100,150.00 | $500.75 | $350.00 | $150.75 | $100,300.75 |
After two payments, the balance is $300.75 higher than at origination. The second month’s interest includes 75 cents attributable to interest on the first capitalized shortfall.
Suppose a contract later requires a $108,000 balance to amortize over the remaining 25 years at a fixed 6.00% rate. The resulting monthly principal-and-interest payment would be about $695.85.
For comparison, a $100,000 balance amortized over 30 years at the same 6.00% rate requires about $599.55 per month. A borrower who had been paying a $350 minimum would face a much larger increase because:
Actual recast calculations depend on the contract’s balance, remaining term, current rate, caps, and timing. This example is not a loan quote.
Some contracts allow a choice among a fully amortizing payment, interest-only payment, and lower minimum payment. Choosing the minimum can create negative amortization when it is below accrued interest.
An interest rate can increase faster than a payment cap permits the required payment to rise. The payment then may not cover current interest, and the difference is added to principal.
An interest-rate cap and payment cap are different. An interest-rate cap limits the rate; a payment cap limits payment growth and can allow unpaid interest to accumulate.
A graduated-payment structure starts with lower payments and schedules increases later. Whether early payments create negative amortization depends on whether they cover accrued interest.
Certain deferrals, restructurings, or hardship arrangements may capitalize unpaid interest or other permitted amounts. The resulting balance treatment depends on the governing program and agreement. A temporary payment pause by itself does not tell the reader whether interest accrues, is waived, remains separately due, or is capitalized.
| Term | Does scheduled payment cover interest? | What happens to principal? |
|---|---|---|
| Fully Amortizing Loan | Yes, plus scheduled principal | Declines to zero under stated assumptions |
| Interest-Only Loan | Yes | Generally remains level during the interest-only period |
| Negative amortization | No | Increases by capitalized unpaid interest |
| Payment deferral | Depends on program | May remain level, accrue separately, or increase |
| Balloon Loan | Usually | Declines but a contractual balance remains due |
| Late or missed payment | Not necessarily made as agreed | Delinquency amounts, fees, and balance treatment depend on contract and law |
Negative amortization should not be confused with negative equity. Negative amortization describes the loan balance increasing. Negative equity means the debt exceeds the asset’s value. Balance growth can contribute to negative equity, but property-value declines can also cause it without negative amortization.
A negative-amortization contract may stop the minimum-payment option when:
At recast, the lender generally recalculates the required payment using the then-current principal, applicable rate, and remaining term. A balance cap limits how much principal can grow before recast; it does not cap the later payment unless the agreement separately says so.
For U.S. consumer mortgages, Regulation Z defines negative amortization and requires disclosures for applicable products. The precise disclosure depends on transaction type and terms.
The ability-to-repay rule generally requires creditors to make a reasonable, good-faith determination that a consumer can repay a covered residential mortgage according to its terms. Qualified Mortgages generally may not provide regular periodic payments that increase principal through negative amortization.
This does not mean every balance capitalization in every credit product is illegal. Mortgage coverage, exemptions, product type, modification status, governing law, and specific facts matter. Current legal or compliance analysis should use the regulation and official interpretations, not a glossary label.
Assuming an on-time payment must reduce principal. A permitted minimum payment can be below interest.
Calling interest-only negative amortization. If all accrued interest is paid, principal does not increase.
Looking only at the initial payment. Recast terms and maximum possible payment can be more important.
Confusing payment caps with rate caps. A payment cap can increase unpaid interest when rates rise.
Ignoring interest on capitalized interest. Once added to principal, the shortfall can generate future interest where the contract permits.
Assuming a balance cap limits every obligation. It may only trigger recast and may exclude fees or advances.
Treating refinancing as guaranteed. Future approval, value, rates, and market access are uncertain.
Lower initial payments are not savings when unpaid interest is added to principal. This article provides general financial education, not individualized mortgage, borrowing, servicing, legal, tax, accounting, or investment advice.
Official U.S. sources were reviewed on September 1, 2026.