Definition
Amortization is the process of paying down a loan over time through scheduled payments that include both interest and principal. With each payment, the loan balance decreases as principal is repaid.
How It Works
In most real estate loans, payments are structured so the borrower pays the same amount each month (during a fixed-rate period). Early in the loan term, a larger share of each payment goes toward interest. Over time, the interest portion declines and the principal portion increases.
Amortization schedule
An amortization schedule is a table showing each periodic payment and how it splits between interest and principal, along with the remaining balance after each payment.
Why It Matters
Amortization affects both cash flow and equity build. Faster amortization (shorter amortization period) typically increases monthly debt service, reducing cash flow, but accelerates principal paydown. Slower amortization improves near-term cash flow but reduces principal paydown.
Investor Uses
- Underwriting debt service: the amortization period is a major driver of payment size.
- Modeling equity growth: principal paydown increases equity even if the property value is flat.
- Evaluating refinance timing: amortization affects the remaining balance at refinance or sale.
- Comparing loan options: 25-year vs 30-year amortization can materially change returns and DSCR.
Key Concepts
- Amortization period: the length of time used to calculate payments (e.g., 30 years).
- Loan term: the time until the loan matures (e.g., 5, 7, or 10 years), which can be shorter than the amortization period.
- Balloon payment: if the term ends before full amortization, the remaining balance is due at maturity.
- Interest-only (IO): a period where payments cover interest only and principal does not amortize.
- Negative amortization: when payments are too small to cover interest, causing the balance to increase.
Example
A property has a loan with a 10-year term and a 30-year amortization. The payment is calculated as if the borrower will repay the loan over 30 years, but the loan matures in 10 years. At maturity, the borrower must refinance, sell, or pay the remaining balance (the balloon payment).
Common Pitfalls
- Confusing term vs amortization: a “10-year loan†may still be amortized over 25–30 years.
- Overstating cash flow durability: refinancing a balloon balance may be difficult if rates rise.
- Ignoring IO reset risk: interest-only periods can end, causing payment shock when amortization starts.
- Not modeling principal paydown: principal reduction can materially improve equity and exit proceeds.