Mortgage refinance break-even: is switching worth it?

Refinancing a mortgage is worth it when the interest you save over the time you will keep the new loan is larger than everything it costs to switch. The quick check is the refinance break-even point: total switching costs ÷ monthly payment saving = months until the switch pays for itself. If you expect to keep the loan well beyond that point, refinancing usually makes sense. For a reliable answer, compare offers over the same remaining term and include the faster fall in your balance, as the worked example below shows.

The examples use euros and hypothetical interest rates. They are illustrations, not market rates, and the maths works the same in any currency. Refinancing rules, early repayment charges and fees differ between countries, lenders and contracts, so check your own loan documents and, for larger decisions, speak to an independent mortgage adviser.

What switching really costs

Before you compare rates, list every cost of leaving your current loan and taking out the new one.

• Early repayment charge. Many fixed-rate loans charge a fee if you repay during the fixed period. The method and any legal cap depend on your contract and local law.
• Arrangement or product fee of the new lender.
• Valuation fee for the property.
• Legal, notary or registration costs, for example to register a new mortgage charge or transfer the existing one.
• Broker fee, if you use one.
• Exit or administration fee of the old lender.
• Lost benefits. An overpayment allowance, a portable loan or a rate cap in your current contract has value too.

Ask your current lender for a redemption statement showing the exact amount needed to repay on a given date, including any charge. That is the only reliable figure.

The simple break-even formula

Break-even (months) = total switching costs ÷ monthly payment saving

Worked example

You owe €200,000 with 20 years left at 4.5% on a repayment (annuity) loan. A new lender offers 3.6% for the same 20 years. Switching costs total €4,500: a €2,500 early repayment charge and €2,000 in fees.

	Current loan	New loan
Balance	€200,000	€200,000
Rate	4.5%	3.6%
Remaining term	20 years	20 years
Monthly payment	€1,265.30	€1,170.22

• Monthly saving: €1,265.30 − €1,170.22 = €95.08
• Simple break-even: €4,500 ÷ €95.08 = 47 months, or just under four years

You can check the payments and test other rates with the mortgage calculator.

Why the simple formula is incomplete

The simple formula only counts the lower payment. With a lower rate and the same term, something else happens too: less of each payment goes to interest and more goes to principal, so your balance falls faster. If you sell or refinance again later, that lower balance is money in your pocket. Our guide on how mortgage amortization works explains why the principal share grows over time.

A more complete comparison after any number of months is:

Net benefit = payments saved + (old loan balance − new loan balance) − switching costs

In the example, that gives:

After	Balance, current loan	Balance, new loan	Interest saved	Net benefit after costs
1 year	€193,687	€193,043	€1,785	−€2,715
2 years	€187,085	€185,832	€3,534	−€966
3 years	€180,178	€178,357	€5,245	€745
5 years	€165,400	€162,575	€8,529	€4,029
10 years	€122,088	€117,782	€15,715	€11,215
20 years	€0	€0	€22,818	€18,318

The true break-even arrives in month 31, more than a year earlier than the simple formula suggests. If you keep the loan for the full 20 years, the switch saves about €18,300 after costs. If you sell after two years, it loses money.

The interest-saved column is the simplest way to think about it: when the term is the same, the net benefit equals the interest you save minus the switching costs.

The term-extension trap

Lenders often present a refinance with a longer term, because the monthly payment drops sharply. In the same example, the new 3.6% loan over 25 years instead of 20:

	Stay (4.5%, 20 years)	Switch (3.6%, 20 years)	Switch (3.6%, 25 years)
Monthly payment	€1,265.30	€1,170.22	€1,012.01
Monthly saving	–	€95.08	€253.29
Simple break-even	–	47 months	18 months
Total interest to the end	€103,672	€80,854	€103,602

The 25-year option looks best on the simple formula: it "pays back" in 18 months. Yet over its life it costs almost exactly as much interest as staying put, and you pay for five more years. The lower payment comes from stretching the debt, not from the lower rate.

A longer term can still be the right choice if you need the cash flow, for example to keep a rental property cash-positive. Just make that decision knowingly, and compare offers over the same remaining term first.

Rolling the costs into the new loan

If you add the €4,500 of costs to the new loan instead of paying them in cash, you borrow €204,500 at 3.6% over 20 years:

• Monthly payment: €1,196.55
• Monthly saving: €1,265.30 − €1,196.55 = €68.75
• Break-even, counting the higher balance: month 34

It works, but it costs a few months, adds interest on the fees and raises your loan to value. If your new rate depends on staying below an LTV threshold, check that the added costs do not push you over it. Loan to value ratio explained shows how lenders calculate it at a refinance.

When the rate gap is small

Now assume the best offer is 4.2% instead of 3.6%, with the same €4,500 of costs and the same 20 years.

• Monthly saving: €32.16
• Simple break-even: about 140 months
• True break-even: month 100, more than eight years

A rate cut of 0.3 percentage points sounds attractive, but here it takes over eight years to pay back. Whether that is acceptable depends on how sure you are that you will keep the loan, and the property, for that long.

When refinancing tends to pay off, and when it does not

It tends to pay off when:

• You expect to keep the loan clearly longer than the break-even point
• The rate gap is large relative to the switching costs
• The balance is large and many years remain
• Your loan to value has fallen into a band with better rates
• Your fixed period is ending anyway, so there is no early repayment charge

Be cautious when:

• You may sell or move within a few years
• The early repayment charge is high and the fixed period ends soon (waiting may be cheaper)
• The offer only looks better because the term is longer
• You would lose a feature you value, such as overpayment rights
• The new deal has a short fixed period followed by an unknown rate

If your fixed period is about to end, the question changes. Without a repayment charge, you are not deciding whether to switch but which new deal to take, and simply accepting whatever rate applies after the fixed period can be expensive. Compare your lender's offer with others in good time.

Refinancing a rental property

For a buy-to-let, a refinance affects more than interest.

• Cash flow. A lower payment raises monthly rental property cash flow. So does a longer term or a switch to interest only vs repayment, but both carry higher lifetime cost or a large balance at the end.
• Equity release. Borrowing more against a higher value frees cash for other investments, but it raises your debt, payments and risk. Treat it as a separate decision from the rate switch.
• Lender criteria. Rental property lenders often test the rent against the new payment and apply their own LTV limits, which may differ from your original loan.
• Tax. How interest and refinancing costs are treated for tax depends on your country and situation. Ask a tax adviser.

How to work out your refinance break-even, step by step

1. Get a redemption statement from your current lender for a realistic switching date.
2. List all switching costs, including fees on both sides and any lost features.
3. Collect offers for the same remaining term as your current loan.
4. Calculate both monthly payments with the mortgage calculator.
5. Work out the simple break-even: costs ÷ monthly saving.
6. Check the balance difference after 3, 5 and 10 years using the yearly schedule, and add it to the payments saved.
7. Compare with your horizon. How long will you realistically keep this loan and this property?
8. Only then look at term changes, as a separate decision about cash flow.

Common mistakes

• Comparing payments with different terms. A longer term always lowers the payment, even at the same rate.
• Ignoring the early repayment charge or assuming it is small.
• Forgetting the old loan's remaining benefits, such as overpayment rights or a cap.
• Using the headline rate only. Fees and conditions can make a lower rate more expensive overall.
• Not checking LTV bands. A small change in valuation can move you into a worse rate band.
• Refinancing just before selling. If you sell before the break-even month, the switch costs money.
• Mixing equity release with a rate switch and calling the result a saving.

Key takeaways

• Simple break-even = switching costs ÷ monthly saving.
• With the same remaining term, the true break-even comes earlier, because the new loan's balance falls faster.
• Net benefit = interest saved − switching costs, when the term stays the same.
• Extending the term lowers the payment but can erase the saving from a lower rate.
• Refinance when you will keep the loan clearly beyond the break-even point, and get advice when the amounts are large.