# Prepayment: What It Is, How It Works, and When It's Worth It

Published: 2026-01-25
Author: Warren Team
URL: https://www.heywarren.com/blog/prepayment-bill

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Prepayment is the act of paying a debt or obligation before it is due — whether on a mortgage, business loan, credit card, or supplier invoice. From a borrower's perspective, prepayment accelerates the return of principal to the lender, reducing the total interest paid over the life of the loan. From a lender's perspective, prepayment is often unwanted: it eliminates the expected interest income stream and creates reinvestment risk (the lender must now redeploy capital at potentially lower yields). This tension between borrower benefit and lender disruption explains why many loans include prepayment penalties — and why understanding them is essential before paying off debt early.

## What Is Prepayment?

Prepayment occurs when a borrower pays back principal in excess of the scheduled amortisation amount — either as a partial lump sum (curtailment) or in full (payoff). In bond markets, prepayment occurs when the issuer redeems bonds before maturity.

**Common prepayment contexts**:
- **Mortgage prepayment**: Paying extra principal on your home loan to reduce the balance faster and cut total interest
- **Business loan prepayment**: Paying off a [term loan](/blog/what-is-a-term-loan) early to reduce interest expense or free up collateral
- **Supplier prepayment (prepayment bill)**: Paying an invoice before the payment due date, sometimes in exchange for an early payment discount
- **Mortgage refinancing**: Effectively a full prepayment of the existing mortgage, replaced by a new loan

## How Prepayment Saves (or Costs) Money

**For borrowers — the interest saving calculation**:

![A single $10,000 extra payment in year 1 saves roughly $40,000 in total interest on a $300,000 30-year mortgage at 7%.](data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20800%20210%22%20width%3D%22800%22%20height%3D%22210%22%20role%3D%22img%22%3E%3Ctitle%3EComparison%3C%2Ftitle%3E%3Crect%20width%3D%22100%25%22%20height%3D%22100%25%22%20fill%3D%22%23f8fafc%22%2F%3E%3Ctext%20x%3D%22230%22%20y%3D%2257.5%22%20text-anchor%3D%22end%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2214%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EStandard%20Payoff%3C%2Ftext%3E%3Crect%20x%3D%22240%22%20y%3D%2225%22%20width%3D%22450%22%20height%3D%2255%22%20rx%3D%226%22%20fill%3D%22%232563eb%22%2F%3E%3Ctext%20x%3D%22702%22%20y%3D%2257.5%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2214%22%20font-weight%3D%22700%22%20fill%3D%22%232563eb%22%3E%24719K%3C%2Ftext%3E%3Ctext%20x%3D%22230%22%20y%3D%22152.5%22%20text-anchor%3D%22end%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2214%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EWith%20Prepayment%3C%2Ftext%3E%3Crect%20x%3D%22240%22%20y%3D%22120%22%20width%3D%22424.618699088552%22%20height%3D%2255%22%20rx%3D%226%22%20fill%3D%22%237c3aed%22%2F%3E%3Ctext%20x%3D%22676.6186990885519%22%20y%3D%22152.5%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2214%22%20font-weight%3D%22700%22%20fill%3D%22%237c3aed%22%3E%24678K%3C%2Ftext%3E%3C%2Fsvg%3E)

*A single $10,000 extra payment in year 1 saves roughly $40,000 in total interest on a $300,000 30-year mortgage at 7%.*

On a $300,000, 30-year mortgage at 7%:
- Standard monthly payment: $1,996
- Total interest paid over 30 years: $418,527
- Total cost: $718,527

If you make one **extra payment of $10,000** in year 1:
- Loan paid off approximately **2 years earlier**
- Interest saved: approximately **$35,000–$40,000**
- Total cost: ~$678,000 — savings of ~$40,000 from a single $10,000 extra payment

This leveraged savings effect occurs because early principal reduction eliminates not just the interest on the $10,000 itself, but all the interest that would have compounded on that $10,000 for the remaining 29 years.

**The [opportunity cost](/blog/formula-of-opportunity-cost) trade-off**: If your mortgage rate is 4%, and you can invest at 7% in a diversified equity portfolio, investing the $10,000 may be better than prepaying — the after-tax return on investment may exceed the after-tax interest saved. At 7% mortgage rates, prepayment is far more attractive because the "guaranteed return" of debt reduction equals the risk-free equivalent of a 7% bond.

## Prepayment Penalties: What to Watch For

Lenders protect expected interest income through **prepayment penalties**:

![Lenders use four main structures to protect against lost interest income when borrowers repay early.](data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20760%20211%22%20width%3D%22760%22%20height%3D%22211%22%20role%3D%22img%22%3E%3Ctitle%3EHierarchy%3C%2Ftitle%3E%3Crect%20width%3D%22100%25%22%20height%3D%22100%25%22%20fill%3D%22%23f8fafc%22%2F%3E%3Crect%20x%3D%22300%22%20y%3D%2220%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22%232563eb%22%2F%3E%3Ctext%20x%3D%22380%22%20y%3D%2254%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2214%22%20font-weight%3D%22700%22%20fill%3D%22white%22%3EPrepayment%20Penalties%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20110%20105.5%20L%20110%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%2230%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22110%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EYield%20Maintenance%3C%2Ftext%3E%3Ctext%20x%3D%22110%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EPV%20of%20lost%20interest%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20290%20105.5%20L%20290%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%22210%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22290%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EStep-Down%20Fee%3C%2Ftext%3E%3Ctext%20x%3D%22290%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EDeclines%20each%20year%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20470%20105.5%20L%20470%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%22390%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22470%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EDefeasance%3C%2Ftext%3E%3Ctext%20x%3D%22470%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3ESubstitute%20gov%26%2339%3Bt%20securiti%E2%80%A6%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20650%20105.5%20L%20650%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%22570%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22650%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EHard%20Lockout%3C%2Ftext%3E%3Ctext%20x%3D%22650%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3ENo%20payoff%20allowed%3C%2Ftext%3E%3C%2Fsvg%3E)

*Lenders use four main structures to protect against lost interest income when borrowers repay early.*

**Yield maintenance**: Compensates the lender for the difference between the loan's interest rate and the current market rate, calculated as the present value of lost future interest. Common in commercial real estate loans.

**Step-down penalty**: Percentage fee that decreases over time (e.g., 5% in year 1, 4% in year 2, 3% in year 3, 2% in year 4, 1% in year 5, then $0). Common in residential mortgages and business [term loans](/blog/terms-loans).

**Defeasance**: Instead of paying off the loan early, the borrower substitutes government securities that replicate the loan's payment schedule. Common in CMBS (commercial mortgage-backed securities). Defeasance is costly but eliminates the yield maintenance calculation.

**Hard lockout**: No prepayment permitted for a defined period (often 2–3 years), regardless of penalty willingness. Common in CMBS and mezzanine lending.

| Loan Type | Typical Prepayment Terms |
|---|---|
| Residential mortgage (conforming) | Usually no penalty for extra payments |
| Residential mortgage (non-QM) | May have step-down penalty |
| Commercial real estate | Yield maintenance or defeasance |
| SBA loan | Prepayment fee for loans >15 years |
| Corporate bond | Call schedule or make-whole provision |
| Personal loan | Varies — check terms before origination |

## Prepayment in Trade: Early Payment Discounts

In business contexts, "prepayment" often refers to paying supplier invoices **before the due date** in exchange for a discount. Standard trade credit terms like "2/10 Net 30" offer:

- **2/10**: 2% discount if paid within 10 days
- **Net 30**: Full amount due within 30 days

This is effectively a very high annualised return:
- Saving 2% to pay 20 days early
- Annualised rate: 2% × (365/20) = **36.5% annualised return**

For businesses with cheap financing, paying invoices early at 2/10 terms is almost always financially attractive — the 36.5% annualised return on early payment exceeds virtually any financing cost.

## Prepayment Risk in Fixed Income

From the [bond and mortgage](/blog/bond-and-mortgage) market perspective, prepayment is a **risk** — specifically prepayment risk in mortgage-backed securities (MBS):

When mortgage borrowers refinance or prepay, the MBS holders receive their principal back sooner than expected and must reinvest at lower rates (since people typically refinance when rates fall). This is called **extension risk** when prepayments slow (when rates rise, borrowers hold their low-rate mortgages) and **contraction risk** when prepayments accelerate.

The **Conditional Prepayment Rate (CPR)** measures the annualised percentage of the mortgage pool expected to prepay in a given month. Mortgage portfolio managers model CPR to price MBS and manage duration.

## Authoritative Sources

For deeper background and primary-source data on this topic, the following authoritative sources are useful starting points:

- [IRS](https://www.irs.gov/)
- [SEC](https://www.sec.gov/)

## Conclusion

Prepayment decisions involve weighing the guaranteed return of eliminating future interest against the opportunity cost of alternative investment returns. For high-rate mortgages (7%+), prepayment is almost always financially justified. For low-rate mortgages (3–4%), the decision depends on alternative investment returns and risk tolerance. Always check for prepayment penalties before making extra payments — especially on commercial real estate loans, where yield maintenance provisions can make early payoff prohibitively expensive. See our guide on [yield spread premium](/blog/yield-spread-premium) for how lenders price mortgage interest rate risk.

Warren at [heywarren.com](https://heywarren.com) helps borrowers and investors model mortgage prepayment economics, break-even calculations, and the impact of early debt payoff on long-term wealth.

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## Related Reading

**More from Warren**:
- [Yield Spread Premium: What It Is and How It Affects Mortgage Costs](/blog/yield-spread-premium)
- [Future Value of an Annuity: Formula, Examples, and How to Calculate It](/blog/future-value-annuity)
- [APY vs. APR: The Difference and Why It Matters](/blog/apy-vs-apr)

**Authoritative sources**:
- [Consumer Financial Protection Bureau — Paying Off Your Mortgage Early](https://www.consumerfinance.gov/ask-cfpb/what-is-a-prepayment-penalty-en-1957/)
- [CFPB — Mortgage Prepayment Penalties](https://www.consumerfinance.gov/owning-a-home/loan-options/)
- [Federal Reserve — Mortgage Disclosure Requirements](https://www.federalreserve.gov/consumerinfo/mortgages.htm)