Negative Amortization
When a loan payment is smaller than the interest due, so the unpaid interest is added to the principal and the balance grows over time instead of shrinking.
Negative amortization (or 'neg-am') happens when your scheduled payment is less than the interest accruing on the loan. The shortfall doesn't disappear — it's tacked onto the principal, so you owe more over time even while making payments. It's the opposite of normal amortization, where each payment chips away at the balance.
Where it shows up in investor lending
Direct neg-am loans are rare today, but the dynamic appears in a few investor contexts:
- Deferred-interest or accrual bridge loans where some interest is added to the balance instead of paid monthly.
- Interest reserves that, once exhausted, can lead to capitalized interest if payments aren't made.
- Construction loans where unpaid accrued interest is sometimes rolled into principal during the build.
- Loan modifications that capitalize past-due amounts onto the balance.
A worked example
A $400,000 accrual loan charges 10% interest but only requires a $2,500/month payment:
Monthly interest due: 400,000 × 10% ÷ 12 ≈ $3,333
Payment made: $2,500
Shortfall added to balance: $833/month
After a year, roughly $10,000 of unpaid interest has been added to principal — the loan now exceeds the original $400,000, and future interest accrues on the larger balance.
Why it's risky
Neg-am erodes equity. If the property's value is flat or falling, a growing balance can push you toward being underwater or leave you facing a balloon payment that comes due larger than expected. It also compounds — interest accrues on interest.
How it's used in investor lending
Most reputable investor products fully amortize or are interest-only, avoiding neg-am. But when evaluating accrual structures, deferred-interest bridge debt, or a construction loan that capitalizes interest, an investor must model the growing balance against the projected exit value and refinance takeout. Always confirm whether your note allows the balance to increase, and size your exit to the payoff at maturity, not the original loan amount.
This is general information, not financial advice.
Frequently asked questions
Is negative amortization common on investor loans?
Direct neg-am loans are uncommon today. Most investor products fully amortize or are interest-only. The dynamic still appears in accrual or deferred-interest bridge loans, construction loans that capitalize interest, and loan modifications that roll past-due amounts onto the balance — so it's worth checking your note.
How do I know if my loan can negatively amortize?
Read the note for any provision that lets unpaid interest be added to principal, or any payment that's set below the full interest amount. Interest-only loans don't amortize but don't grow either; neg-am specifically means the balance can increase. Ask the lender directly if it's unclear.
Why is negative amortization dangerous for investors?
Because the balance grows instead of shrinking, eroding your equity and increasing the payoff due at maturity or sale. If the property's value stays flat or declines, you can end up owing more than it's worth, complicating a refinance or sale and risking a maturity default.