Start With Your Current Deal

Before you look at a single new rate, dig out your latest mortgage statement or log into your lender's online portal. You need four numbers: your current interest rate, your outstanding balance, your remaining term, and your monthly payment. Write them down. Without them, any comparison you make is guesswork.

Next, work out whether you are on a fixed rate, a tracker, a discount, or the lender's standard variable rate (SVR). This matters enormously. If your fixed deal has already ended and you have drifted onto the SVR, you are very likely overpaying. SVRs are typically several percentage points above the competitive deals on the market, and lenders rely on borrowers not noticing. Thousands of households slip onto an SVR every year simply because nobody picked up the phone.

Finally, check your early repayment charge (ERC). Most fixed deals carry one if you leave before the end of the term. It is usually a percentage of the balance — commonly between 1% and 5% — and it tapers the closer you get to the end date. If you are within six months of your deal ending, most lenders will let you arrange a new rate in advance without penalty. That window is the sweet spot for planning.

Why Remortgaging Can Cut Your Costs

Remortgaging means taking out a new mortgage, usually with a different lender, to pay off the existing one. The appeal is straightforward: a lower interest rate means lower monthly payments, and over the remaining term that can add up to a serious sum.

Say you owe £180,000 on a 20-year term at 5.5%. Your payment is roughly £1,237 a month. Move that same balance to a 4.2% rate over 20 years and you are paying around £1,107 — a saving of about £130 a month, or £1,560 a year. Over a five-year fixed term, that is £7,800 in your pocket. On a larger balance, the gap widens further.

There are other gains too. You might switch from a variable rate to a fixed one and gain certainty, which matters if your budget is tight. You could extend the term to reduce the monthly figure, though be careful — stretching the term means paying more interest overall. Or you could shorten the term and pay more each month to clear the debt sooner. Remortgaging is also an opportunity to borrow a little extra for home improvements, debt consolidation or a deposit elsewhere, provided the numbers stack up and your lender agrees.

Compare Rates Properly, Not Just the Headline

The rate advertised on a comparison table is only part of the story. When you compare deals, look at the APRC — the annual percentage rate of charge — which factors in fees and assumes you keep the mortgage for the full term. It gives a fairer picture than the headline rate alone.

Watch for these costs, which vary widely between products:

• Arrangement fee: can range from nothing to over £1,500, sometimes added to the loan.
• Valuation fee: some lenders offer free basic valuations, others charge a few hundred pounds.
• Legal fees: a remortgage usually needs conveyancing, though many lenders cover this.
• Booking or application fee: sometimes charged separately.
• Exit fee: an administration charge from your current lender, typically £75 to £300.
• Broker fee: if you use an adviser, check whether they charge a flat fee, a percentage, or take commission from the lender.

A deal with a very low rate and a £1,499 fee can cost more than a slightly higher rate with no fee. Do the arithmetic over the fixed period, not just the first month. Add the total fees to the total interest paid across the deal term and compare that combined figure.

Run the Break-Even Calculation

The simplest way to judge whether switching is worth it is to work out how long it takes for your monthly saving to cover the switching costs.

Add up all the fees you will pay to move — arrangement, valuation, legal, exit, broker. Then divide that total by your monthly saving. The answer is the number of months before you break even.

• Fees of £1,200 and a saving of £120 a month: break-even in 10 months.
• Fees of £1,200 and a saving of £40 a month: break-even in 30 months.

If you plan to stay in the property well beyond the break-even point, switching makes sense. If you might sell or move within that period, the maths quickly turns against you — and you may face an ERC on the new deal as well. Be honest about your plans over the next few years.

Practical Steps to Get Moving

Give yourself two to three months before your current deal ends. Rates move, paperwork takes time, and you want room to walk away from a bad offer without pressure.

• Check your credit file with the main agencies and fix any errors before applying. Lenders price on risk.
• Gather your documents: payslips, bank statements, proof of address, and details of any other debts.
• Get an affordability check in principle from a couple of lenders so you know your realistic borrowing range.
• Speak to your existing lender too. They sometimes offer existing customers a retention product that beats the open market, and it avoids legal and valuation costs.
• Consider a whole-of-market broker if your circumstances are unusual — self-employed income, a recent career change, or a property that is not standard construction.

One caution: if you are extending your term to lower the monthly payment, remember you are also extending the period over which interest accrues. A lower payment is not automatically a cheaper mortgage. If the goal is genuinely to reduce cost, compare the total interest paid over the life of the loan, not just the figure leaving your account each month.

Know When Not to Switch

Remortgaging is not always the right answer. If you are deep into a fixed deal with a substantial ERC, the penalty can wipe out the saving. If your loan-to-value has risen because property values have fallen, you may not qualify for the best rates. And if you have missed payments or taken on new credit recently, you may be offered worse terms than you already hold.

In those cases, overpaying your existing mortgage — even modestly — can be more effective than switching. Many lenders allow overpayments of up to 10% a year without penalty, and every extra pound reduces the balance that interest is charged on.

Review your deal annually, even when you are not actively looking to move. Fifteen minutes with your statement and a comparison table can tell you whether a worthwhile opportunity exists. Staying on top of it is one of the simplest ways to keep your housing costs under control.