Refinancing vs extra repayments

Two paths to lower mortgage cost

Borrowers seeking to reduce their mortgage cost have two main levers: refinance to a lower rate, or pay extra principal on the existing loan. Both reduce total interest paid; both have different cost profiles, different friction, and different optimal use cases.

The choice between them is not always obvious. A small rate difference may make refinancing not worth the upfront cost. A large rate difference may make it overwhelmingly attractive even after fees. Extra repayments can save more than a marginal refinance and produce no upfront cost, but they cannot deliver the lifetime savings of a meaningful rate reduction.

Understanding when each path dominates — and when they should be combined — is the discipline that separates active mortgage management from passive servicing.

What refinancing achieves

Refinancing replaces the existing loan with a new one, typically at a lower rate. The new loan pays out the old loan, and the borrower’s debt is now governed by the new terms.

The savings come from the rate reduction, applied across the remaining loan balance for the remaining term. For a $400,000 mortgage with 25 years remaining at 6.4% refinanced to 5.4%:

• Existing monthly repayment: ~$2,679
• New monthly repayment: ~$2,438
• Monthly saving: ~$241
• Annual saving: ~$2,892
• Lifetime saving (over remaining 25 years): ~$72,300

A 1% rate reduction produces substantial savings on a typical-sized mortgage over a typical remaining term. The savings scale roughly linearly with the rate reduction and the remaining loan size — a 0.5% reduction produces about half the saving; a $200,000 loan produces about half the saving of a $400,000 loan.

The savings are not free. Refinancing carries upfront costs that reduce the net benefit.

What refinancing costs

The typical cost stack:

Discharge fee on the existing loan. Usually $200–$400. Charged by the existing lender to release the security and close the loan.

Establishment fee on the new loan. Usually $300–$1,000. Charged by the new lender to set up the new loan.

Valuation fee. Usually $200–$800, depending on the property and market. Required by the new lender to confirm the security value.

Government registration fees. Vary by jurisdiction, typically $100–$300, for transferring the security charge.

Legal fees. $300–$1,500, depending on the complexity and whether the borrower uses a solicitor or conveyancer.

Mortgage insurance if the new loan crosses a higher LVR band than the existing one. Can be $5,000–$20,000+ on a typical residential loan and is the largest single potential cost.

Break costs if the existing loan is on a fixed rate and is being broken before the fixed period ends. These can be substantial — sometimes tens of thousands of units of currency on large loans during periods of falling rates. The mechanic is that the lender’s hedging position on the fixed-rate loan has economic value, and the break cost reimburses that value to the lender. A borrower with a fixed-rate loan should always quantify break costs before committing to refinance.

For a typical residential refinance without break costs, the total cost runs $1,500–$4,000. With break costs on a fixed-rate loan, the figure can be much higher.

What extra repayments achieve

Extra repayments apply additional principal beyond the scheduled payment, reducing the loan balance and the interest charged on the next period. The savings come from the compounding effect of reduced principal across the remaining loan term.

For the same $400,000 mortgage at 6.4% over 25 years, applying an extra $300 per month:

• Loan paid off in: ~21 years instead of 25
• Total interest saved: ~$74,000
• Years saved: ~4

The savings are comparable in magnitude to the refinance savings — but they cost zero upfront and require no new loan, no new application, and no friction with the existing lender (assuming the existing loan permits extra repayments without penalty).

For the same loan with $500 per month in extra repayments, savings rise to roughly $112,000 with about 7 years saved. The relationship between extra repayment amount and savings is not linear — larger extra repayments produce disproportionately larger savings because they reduce the principal earlier, when interest charges are highest.

When refinancing saves more

Refinancing dominates extra repayments when the rate reduction is meaningful and the remaining term is long.

A useful rule of thumb: if the available new rate is 0.5 percentage points or more below the existing rate, the lifetime savings from refinancing typically exceed the savings from realistic extra repayments. Above 1 percentage point of rate reduction, refinancing is overwhelmingly the dominant choice.

The math behind this: refinancing reduces interest on the entire remaining balance for the entire remaining term. Extra repayments reduce interest on the principal as it is reduced — only on the amounts paid extra, only from the time they are paid. For typical residential loans, the rate-reduction effect of refinancing dominates in scenarios with meaningful rate gaps.

A worked comparison. Same $400,000 loan, 25 years remaining at 6.4%. Two strategies:

Refinance to 5.4%: lifetime saving ~$72,300 minus refinance cost of $3,000 = net ~$69,300.

Extra repayments of $300/month: lifetime saving ~$74,000 with no upfront cost.

In this case, the two strategies produce similar net savings. But if the borrower can do both simultaneously — refinance to the lower rate AND continue $300/month extra repayments at the new rate — the combined saving is approximately $130,000 net.

The non-zero answer is often “do both.”

When extra repayments save more

Extra repayments dominate refinancing when:

The available rate reduction is small. A 0.1–0.3% rate reduction may not justify the refinancing fees. The breakeven point is the period over which the rate-reduction savings cover the upfront costs. For a $300,000 loan with $3,000 in refinancing costs and a 0.2% rate reduction, the rate saving is roughly $600 per year — making the breakeven five years. If the borrower expects to hold the loan less than five years, extra repayments are the cleaner choice.

Break costs on a fixed-rate loan are large. A fixed-rate loan with three years left in its fixed period and $25,000 in break costs effectively requires the rate reduction to recover $25,000 plus other fees before any net saving accrues. Many “attractive” rate gaps disappear once break costs are computed.

The remaining term is short. A loan with five years remaining has limited time for rate-reduction savings to amortise the upfront cost. Extra repayments work proportionally to the remaining term and produce more reliable savings on short-remaining-term loans.

The borrower has no appetite for refinancing friction. Refinancing requires reapplication, valuation, document signing, and a temporary period of two loans during transition. Some borrowers prefer the simplicity of staying with their existing lender and accelerating payoff through extra repayments, even at modest financial cost.

How to compare for a specific loan

A pragmatic comparison sequence:

1. Quantify the available new rate. Get genuine refinance quotes — not advertised rates — that reflect the borrower’s specific LVR, credit profile, and preferred features.

2. Quantify break costs on existing loan. Particularly important for fixed-rate loans. Ask the existing lender for a break cost quote.

3. Quantify total refinancing costs. Discharge, establishment, valuation, registration, legal, plus any LMI if crossing a higher LVR band.

4. Compute rate-reduction savings over the remaining term. Using a repayment calculator, model the existing loan’s total cost and the new loan’s total cost. Subtract to get the gross saving.

5. Compute net refinancing saving. Gross saving minus total upfront costs.

6. Compute extra repayment savings at a realistic level. Using an extra repayment calculator, model the existing loan with a sustainable extra payment amount.

7. Compare net refinance saving to extra repayment saving. The higher figure is the dominant strategy on its own.

8. Compute the combined strategy. Refinance plus continue extra repayments at the new rate. This is often the best total outcome.

Common pitfalls

Comparing headline rates rather than comparison rates. Two loans with the same headline rate can have very different fees, and the headline rate alone misleads on the actual saving available.

Forgetting break costs on fixed-rate loans. The single largest source of unexpected cost in mortgage refinancing. Always confirm break costs before committing.

Ignoring LMI thresholds. A refinance that takes the LVR back above 80% can trigger mortgage insurance, often costing more than the rate-reduction savings. Confirm the new LVR carefully.

Stopping extra repayments after a refinance. A refinance to a lower rate makes each dollar of extra repayment slightly less powerful (because the interest saved per dollar of extra payment is lower at the lower rate), but the discipline of continued extra repayments still produces substantial lifetime savings. Continuing them is almost always the better choice.

Refinancing too frequently. Each refinance carries upfront costs. Refinancing every two years to chase modest rate reductions can produce a poor net outcome once the cumulative fees are tallied.

How the calculator helps

The HoldingCost mortgage repayment calculator models the total cost of a loan at any rate and term. The extra repayment calculator models the savings of additional principal contributions. Together, they provide the inputs for a like-for-like comparison of refinancing and extra repayment strategies.

The debt payoff optimiser calculator extends the analysis to handle multiple debts simultaneously, identifying the combination of strategies that produces the lowest total interest cost across an entire debt portfolio.

Use them whenever a refinance opportunity arises — to confirm the saving is genuine after all costs, to compare against the alternative of staying put with extra repayments, and to quantify the combined strategy of doing both.

Practical takeaways

Refinancing and extra repayments are complementary tools rather than alternatives. Refinancing produces the larger savings when rate reductions are meaningful and remaining terms are long; extra repayments produce reliable savings without upfront cost and work especially well on shorter remaining terms or when refinancing economics are marginal. The combination — refinance to the lower rate AND continue extra repayments at the new rate — typically produces the strongest net outcome. The discipline is to model both for the specific loan rather than relying on rules of thumb.

This guide is general information only and does not constitute financial advice. Loan products, fees, and break-cost structures vary significantly by lender and jurisdiction. Confirm specific terms with your lender and a qualified financial adviser before relying on any modelled saving.