Mortgage choices
Mortgage Overpayment vs Offset Mortgage
A practical comparison of two ways to reduce mortgage interest: paying extra into the loan or linking savings through an offset account.
Mortgage overpayments and offset mortgages both aim to reduce interest, but they work differently. An overpayment reduces the mortgage balance directly. An offset mortgage links savings to the mortgage so interest is charged on a smaller net balance. Use the mortgage overpayment calculator and offset mortgage calculator to compare your own numbers.
The short version
Overpayments are usually simpler: extra money goes into the mortgage and reduces future interest. Offset mortgages can be more flexible because savings remain accessible, but the mortgage rate or account fee may be higher.
The better option depends on:
- Mortgage rate.
- Offset rate or product fee.
- Savings balance.
- Tax on savings interest.
- Whether you need emergency access to cash.
- Overpayment limits and early repayment charges.
Option A: mortgage overpayment
An overpayment is extra money paid into the mortgage on top of the normal monthly payment. It can shorten the mortgage term, lower future interest, or sometimes reduce future payments depending on lender rules.
Overpayments work best when the mortgage rate is meaningfully higher than the after-tax return you could safely earn elsewhere and you do not need the cash back quickly.
Use the mortgage overpayment calculator to estimate interest saved and time saved.
Option B: offset mortgage
An offset mortgage links savings to the mortgage balance. If the mortgage is 200,000 and linked savings are 30,000, interest may be charged as though the balance were 170,000.
This can be attractive if you want the interest-saving effect of using savings against the mortgage while keeping access to cash. The tradeoff is that offset products may have different rates, fees, or eligibility rules.
Use the offset mortgage calculator to compare offset savings against a standard mortgage and savings account.
Example scenario
Imagine a 200,000 mortgage at 5% with 25 years remaining and 20,000 in savings.
If you overpay 20,000, the mortgage balance falls to 180,000 and future interest is calculated on the lower balance. If you offset 20,000, interest may also be calculated on a net 180,000, but the savings remain available.
If the offset mortgage charges a higher rate or fee, the flexibility may cost more. If savings interest would be taxed heavily, the offset can look stronger because the interest saving is not the same as earning taxable savings interest.
Decision checklist
- Do you need access to the money later?
- Does your lender cap overpayments?
- Are there early repayment charges?
- Is the offset mortgage rate higher than the standard rate?
- Would savings interest be taxed?
- Are you comparing the same term and fees?
Caveats
Mortgage choices can affect cash flow, flexibility, tax, and risk. Calculators can help you compare scenarios, but they are not personal financial advice. Product fees, lender rules, and future rates can change the outcome.
Tools mentioned in this article
Reader questions
Is overpaying always better than saving?
No. It depends on rates, tax, fees, access to cash, and whether you have other higher-priority debts or savings needs.
Can I get overpayments back?
Sometimes, but not always. Some mortgages allow payment holidays or borrowing back overpayments, but many do not.
Does an offset mortgage pay savings interest?
Usually the linked savings do not earn normal interest. Instead, they reduce mortgage interest charged.
Which calculator should I start with?
Start with the overpayment calculator if you plan to pay extra into the mortgage. Start with the offset calculator if you want to compare linked savings against a standard mortgage.
