Loans
Amortization Shock: Where Your Early Mortgage Payments Go
Published November 4, 2026 · 2 min read
On a 30-year mortgage, most of each early payment covers interest. Here is the math on a $300,000 loan — and what changes it.
Same payment, shifting mix
A standard fixed-rate mortgage has the same monthly payment for its whole life. What changes is the split inside that payment. Each month, interest is charged on the balance still owed. Early on, the balance is large, so interest takes most of the payment. As the balance shrinks, interest shrinks too, and more of the same payment goes toward principal.
Monthly interest = remaining balance × (annual rate ÷ 12)
A worked example
Take a $300,000 loan at a fixed 6.5% annual rate for 30 years (360 monthly payments). The monthly principal-and-interest payment is about $1,896.20. Taxes, insurance, and fees are not included.
| Milestone | Amount |
|---|---|
| First month’s interest | $1,625.00 |
| First month’s principal | $271.20 |
| Paid in first 5 years | about $113,772 |
| …of which interest | about $94,605 |
| …of which principal | about $19,167 |
| Balance after 5 years | about $280,833 |
| Month principal first exceeds interest | month 233 (year 20) |
| Total interest over 30 years | about $382,633 |
In other words, after five years of payments — roughly $114,000 — the balance has fallen by only about $19,000. That surprise is what people sometimes call amortization shock.
This is not a hidden fee
Front-loaded interest is not a trick. It is simply interest charged on what you still owe. You are not paying extra interest early; you owe more money early. The schedule follows directly from the rate and the balance.
What changes the picture
- Shorter term: the same loan over 15 years costs about $2,613 a month but roughly $170,000 in total interest instead of $383,000.
- Extra principal payments: any extra amount reduces the balance immediately, which lowers every future interest charge. Check whether your loan has prepayment terms first.
- Lower rate: even a small rate difference compounds across 360 months.
- Larger down payment: a smaller starting balance means less interest from the very first month.
The right choice depends on your budget, emergency savings, other debts, and the terms of your loan. A lender or qualified adviser can explain options specific to your situation.
Sources & notes
- Figures computed by NumberChan with the standard fixed-rate amortization formula; rounded to the nearest dollar where noted.
This article is for general education and is not financial, tax, or legal advice.