Your fixed rate is ending. Here's what actually happens next.

There is a date sitting in your mortgage paperwork that will do more to your monthly budget than almost any decision you make this year. It's the day your fixed rate ends. And unlike most financial deadlines, nothing happens to warn you - no penalty, no phone call, no locked door. Your payment simply goes up, and keeps going up, until you do something about it.

What actually happens on the day

Your fixed rate is a temporary arrangement bolted onto a much longer mortgage. When the fix expires, the mortgage doesn't end - it reverts. You roll onto the lender's standard variable rate, a number the lender sets at its own discretion and can change more or less whenever it likes.

This is the part people find genuinely surprising: it's automatic. There's no application, no consent, no moment where someone asks if you're sure. The direct debit just collects a larger number the following month. Lenders do write to you - typically around six months out - but that letter arrives among everything else, and it's remarkably easy to file it under deal with later.

“The standard variable rate isn't a punishment. It's a default. That's exactly what makes it so expensive - nothing has to go wrong for you to end up there.”

The payment shock, in real numbers

Take a household with £200,000 outstanding and 20 years left to run, coming off a 2.5% fix - the kind of rate that was ordinary a few years ago.

The middle column is the one to sit with. Even doing everything right - shopping around, switching promptly, getting a competitive rate - this household is £2,466 a year worse off. That's not a failure of planning; it's the market. The job isn't to avoid it, it's to avoid the third column on top of it.

Because the gap between switching and not switching is £346 a month. Six months of I'll sort it soon costs roughly £2,075 - real money, for an outcome nobody chose.

The timeline that actually matters

Almost every lender will let you reserve a new deal three to six months before your current one ends. This window is the single most useful thing to know, and it works asymmetrically in your favour.

1. Six months out - find your end date. It's on your original offer and your annual statement. Put it in your calendar with a reminder.
2. Five to six months out - ask your existing lender what they'd offer you. This is a product transfer, and it's the baseline everything else has to beat.
3. Four to five months out - check the wider market, either yourself or through a broker. Compare total cost including arrangement fees, not headline rates.
4. Three to four months out - lock something in. If rates fall before completion you can usually switch to the better deal; if they rise, you're protected.
5. The month it ends - confirm the new rate has actually started. Mistakes happen, and a month on the SVR is expensive.

Locking early is close to a free option. You're reserving a rate you can generally abandon if something better appears. The only real cost is a bit of admin - which is why leaving it until the last fortnight is such a poor trade.

Product transfer or full remortgage?

A product transfer means staying with your current lender on a new rate. It's quick, usually skips a fresh affordability check, and often carries no legal or valuation fees. If your circumstances have changed - a lower income, a spell of self-employment, a fall in your property's value - this is frequently the most achievable route, precisely because the lender isn't reassessing you from scratch.

A full remortgage moves you to a new lender. It takes longer, involves a valuation and conveyancing, and you'll be underwritten properly. In exchange you get the whole market. On a large balance, a modestly better rate easily outweighs a few hundred pounds of fees - but on a small balance it often doesn't, and the fees quietly eat the gain.

The honest test is total cost over the deal period: the payments plus every fee, compared side by side. A 4.3% rate with a £1,499 fee can be worse than 4.5% with no fee, depending on your balance. Headline rates are marketing; the total is the number.

One lever worth pulling first

Your rate depends on your loan-to-value - the balance as a percentage of the property's value. Lenders price in bands, typically at 60%, 75%, 80%, 85% and 90%. Landing just the wrong side of a threshold can cost you a visibly worse rate for the whole deal period.

If you're close to a band, a modest overpayment before you apply can tip you under it, and the saving lasts for years. Most fixed deals allow overpayments of up to 10% of the balance a year without penalty - but check your own offer document first, because early repayment charges are real and they're not small.

It's also worth knowing your property's likely value rather than guessing. If prices in your area have risen since you bought, your LTV may already be better than you assume, and nobody will point that out for you.

If the new payment looks unaffordable

Say so early, to your lender, before the fix ends and before you miss anything. UK lenders have regulatory obligations to help customers in difficulty, and the range of options - extending the term, a temporary switch to interest-only, a payment arrangement - is far wider while your record is clean than after a missed payment.

Free, impartial help exists too, and none of it charges: StepChange, National Debtline and Citizens Advice all deal with mortgage worries specifically. Asking early is not an admission of failure. It's the cheapest move available.

This is general information about how UK mortgage deals work, not personal advice. Your rate, balance, term and circumstances all change the answer - and if the sums are significant, a regulated mortgage adviser who can see the whole picture is usually worth the fee.