Fixed vs Variable Mortgage: It's Insurance, Not a Bet

The fixed vs variable mortgage question is usually framed as a forecast. Will rates go up, in which case fix, or down, in which case track and save? Every comparison page, every mortgage adviser's small talk, every Reddit thread runs on that same axis. It treats your remortgage like a hand of poker against the market.

That framing is wrong, and it costs people money. A fixed rate is not a bet you win if rates rise and lose if they fall. It is insurance. You are paying a lender to carry the risk of your payment jumping, and like all insurance it comes with a premium baked into the price. Once you see it that way, the question stops being "where are rates going" (which nobody knows) and becomes "what happens to my household if I am wrong", which is a question you can actually answer. (If you have not committed to buying at all yet, the rent vs buy equation is the prior question.)

Contents

• Fixed, tracker, SVR: what each one actually is
• A fix is insurance, not a bet
• Why "will rates rise or fall" is the wrong question
• The certainty premium, with real numbers
• Two-year or five-year fix
• When variable actually makes sense
• Never sleepwalk onto the SVR
• Frequently Asked Questions

What each one actually is

Four rate types cover almost every UK mortgage, and the difference between them is entirely about who controls the rate.

A fixed rate is locked for a set period, usually two or five years. Your payment cannot change for that term whatever the Bank of England does. When the term ends, you revert to the lender's Standard Variable Rate unless you take a new deal.

A tracker follows the Bank of England base rate plus a fixed margin, by contract. If the base rate is 3.75% and your margin is 1%, you pay 4.75%, and when the base rate moves your rate moves by exactly the same amount the following month. The margin is fixed; the base rate is not.

A discount rate is a fixed discount off the lender's SVR, not off the base rate. The discount is fixed but the SVR underneath it can move whenever the lender chooses, so your pay rate is less predictable than a tracker's.

The Standard Variable Rate is the lender's default rate, set entirely at its own discretion. It drifts roughly with the base rate but the lender can change it by any amount at any time. It is almost always the most expensive option, and it is the one you land on by accident. The full menu of mortgage products, including offset and interest-only, sits in UK mortgage types.

A fix is insurance, not a bet

Strip away the jargon and a fixed rate is a contract where the lender agrees to absorb the risk that rates rise during your term. That is insurance. You are the policyholder, the lender is the insurer, and the thing being insured is your monthly payment.

Insurers do not give cover away. They price it to come out ahead on average, because if they did not they would go bust. The price of a fix is set against the same market that prices everything else: the interest-rate swaps market, where banks buy and sell the right to fixed payments years into the future. When you fix, the lender hedges its risk in that market and charges you for the hedge. The premium is the gap between what you pay to fix and what you would have paid, on average, by riding the variable rate instead.

So the honest way to read a fixed rate is: this is the amount I am willing to pay for the certainty that my payment will not move. Sometimes that certainty is worth a lot, when a rate rise would genuinely sink you. Sometimes it is worth very little, when you could shrug off a few hundred pounds a month. The product is the same; the value depends entirely on your situation, not on a forecast.

The wrong question

The reason "will rates rise or fall" is the wrong question is that you are not the first person to ask it. Thousands of traders whose job is pricing interest rates have already asked it, with better information than you, and their collective answer is sitting inside the fixed rate you are being quoted.

If the market were confident rates would tumble, five-year fixes would already be priced cheap to reflect it. If it expected rises, they would be priced dear. The expectation is in the number. To "beat" the fix by going variable, you do not just need rates to fall. You need them to fall by more than the market already expects, consistently, over your whole term. That is not a forecast, it is a wager against the people who set the odds.

This is why treating the decision as prediction is a category error. Fix for protection, not prediction. The market has already done the predicting, and it has built its best guess into the price either way.

The certainty premium

Put real numbers on it. Take a £200,000 mortgage over 25 years in June 2026.

• A 5-year fix at around 5.6% costs roughly £1,240 a month.
• A tracker at base rate plus 1%, so 4.75% today, costs roughly £1,140 a month.

The tracker is about £100 a month cheaper right now. That £100 is the certainty premium, viewed from the other side: it is what the fixer pays, every month, for a payment that cannot move. Over the five years, if nothing changed, the fixer would hand over something like £6,000 for that peace of mind.

But things change. If the base rate climbed 1.5 points to 5.25%, the tracker would jump to 6.25% and cost about £1,320 a month, now £80 more than the fix. The tracker borrower who could not absorb that swing is the one who needed the insurance and did not buy it. The tracker borrower who had £80 a month of slack barely notices, and pockets the saving in every month rates stay low.

Same product, opposite verdicts, decided entirely by how much headroom each household had. That is the maths worth doing, not a guess about the base rate.

Two-year or five-year fix

Once you have decided to insure, the term is the next question, and it is the same insurance logic applied to time. A five-year fix buys you more certainty, for longer, usually at a similar or slightly higher rate than a two-year. A two-year fix is cheaper certainty but it runs out sooner, dropping you back into the market in 24 months to do this all again, paying new arrangement fees and hoping rates are kind.

The catch on both is the lock-in. Leave a fix early, or overpay beyond the usual 10%-a-year allowance, and you trigger an Early Repayment Charge, typically 1% to 5% of the balance, tapering down as you move through the term. On a £200,000 balance a 5% charge is £10,000. That is the price of buying certainty you later decide you do not want, so match the term to how long you are confident you will stay put. The overpayment-allowance rules that sit alongside ERCs are covered in should I overpay my mortgage.

The longer fix also costs you optionality, which is why I lean toward a lower committed payment with room to manoeuvre rather than locking everything down. For the full case on keeping flexibility, see 40-year mortgage UK: stretched, trapped, or smart?.

When variable actually makes sense

Variable is the right call more often than the "always fix" crowd admits, but only in specific situations:

• You could comfortably absorb a sharp rise out of income or savings, so you do not actually need the insurance.
• Your balance is small or you are near the end of your term, so even a big rate move is small money in absolute terms.
• You expect to repay or move soon and want to dodge the Early Repayment Charge a fix would impose.
• You want the option to overpay heavily without penalty, which most trackers allow and most fixes cap at 10% a year.

In every one of those cases the common thread is the same: the downside of a rate rise is survivable, so paying the premium for certainty is money you do not need to spend.

Never sleepwalk onto the SVR

Whatever you choose, the one genuinely expensive outcome is doing nothing. When a fix or tracker ends, you revert automatically to the Standard Variable Rate, which averaged about 7.1% in June 2026 against roughly 5.6% for a new fix. That gap, around 1.5 percentage points, is pure waste, and the lender is happy to let you pay it.

The scale is not trivial. The FCA's Mortgages Market Study back in 2019 found roughly 1.2 million borrowers paying a "loyalty penalty" by sitting on a reversion rate they could easily have left, with one in ten of them losing over £1,000 a year. The fix-versus-variable decision matters, but it matters far less than the simple act of not lapsing onto the SVR. The day your deal ends is the day to act, which is what remortgaging is for, and the remortgage break-even calculator shows whether switching even mid-deal beats waiting.

Frequently Asked Questions

What is better, a fixed or variable mortgage?

Neither is universally better, because they solve different problems. A fix buys certainty and protects you if rates rise; a variable rate is usually cheaper today and rewards you if rates stay low or fall, at the cost of risk. The right answer depends on one thing: whether a sharp payment rise would genuinely hurt your household. If yes, fix. If you could absorb it, variable is a reasonable gamble.

Should I fix for 2 years or 5 years?

A five-year fix buys longer certainty and saves you a second round of arrangement fees in two years' time, but locks you in for longer with a bigger Early Repayment Charge if you need out. A two-year fix is cheaper to exit and suits anyone who might move, repay, or expects rates to be meaningfully lower soon. Match the term to how long you are confident your circumstances will not change.

Is a 3-year fixed mortgage a good idea?

A three-year fix is a sensible middle ground when you want more certainty than two years but do not want to commit for five. They are less common, so the rate is sometimes a little higher for the smaller market, but the logic is the same as any fix: you are buying a fixed length of protection, and three years can be the right amount if that is roughly how long you expect your situation to hold.

What is the disadvantage of a variable mortgage?

The payment can rise with no warning and no cap. On a tracker your rate moves with the Bank of England base rate; on a Standard Variable Rate the lender can move it whenever it likes. If rates climb and your budget has no slack, a variable mortgage can turn an affordable payment into an unaffordable one within months. That is exactly the risk a fix exists to remove.

Will my mortgage payment change if I am on a fixed rate?

Not because of interest rates, for the length of the fix. Your rate is locked, so a base-rate change does not touch you until the deal ends. Your payment can still change for other reasons: a change to your buildings insurance or service charge if they are collected with the mortgage, or the automatic jump to the much higher Standard Variable Rate the moment your fixed term expires and you have not arranged a new deal.

The Psychology of Money - Morgan Housel - The clearest book on why how a financial decision feels matters as much as the spreadsheet. Exactly the lens the fix-versus-variable choice needs. (Affiliate link - we may earn a small commission at no extra cost to you.)

This article is general information, not personal financial advice. UK mortgage rates and the Bank of England base rate move constantly, and the figures here are accurate as of June 2026. Early repayment charges, reversion rates, and product terms vary by lender. If you are unsure which deal fits your circumstances, consider speaking to an FCA-authorised mortgage broker.