// Source citations for the factual claims in this guide (kept out of the // rendered tree: flow-level MDX comments break Next scroll-on-navigation). export const sources = [ "Worked example computed with the formulas in site/lib/remortgage.ts (computeRemortgage, monthlyPayment, balanceAfter): £200,000 balance, 20 years remaining, illustrative 2-year deal at 4.5% with a £999 arrangement fee vs an illustrative 7% SVR → deal £1,265.30/mo, SVR £1,550.60/mo (£285.30/mo gap); extra interest in the first SVR month £416.67 (£200,000 × 2.5%/12); three months on the SVR costs £1,249.07 more in interest than three months on the deal; switching saves £8,903.89 vs the SVR over the 24-month window after the fee.", "The 7% SVR figure is the calculator's illustrative default (DEFAULT_SVR_PERCENT in site/lib/remortgage.ts), not a market quote; real SVRs vary by lender.", "Mortgage Charter, HM Treasury, https://www.gov.uk/government/publications/mortgage-charter/mortgage-charter, retrieved 2026-06-12: customers of signatory lenders approaching the end of a fixed rate deal can lock in a new deal up to six months ahead, and can request a better like-for-like deal with their lender right up until the new term starts, if one is available.", ];

Guide · 5 minute read · Updated 2 Jul 2026

When should I start remortgaging before my fix ends?

Start about six months before your fixed rate ends. Most lenders let you lock a new deal three to six months ahead, Mortgage Charter signatories commit to six, and having a deal lined up stops you drifting onto the expensive standard variable rate.

Why six months, not six weeks

When a fixed deal ends and you do nothing, your lender moves you onto its standard variable rate (SVR), which is usually well above the fixed rates on offer. The whole game is to have the next deal ready to start the day the old one finishes, and that takes longer than people expect.

Lenders generally let you apply for and lock in a new rate three to six months before your current deal ends; the exact window varies by lender, so check yours. Under the Mortgage Charter, lenders covering most of the UK market committed to letting customers lock in a new deal with their existing lender up to six months ahead, and to letting them swap to a better like-for-like deal right up until the new term starts if one becomes available.

That last part matters. Locking early with a charter signatory is close to a one-way bet: you secure today's rate as a ceiling, and if your lender launches a cheaper equivalent before your switch date, you can take that instead. Waiting gains you almost nothing.

Product transfer or full remortgage?

You have two routes, and the six-month head start gives you time to compare both.

A product transfer means taking a new deal with your current lender. It is fast, often paperwork-light, and usually skips a new affordability assessment, valuation and conveyancing. The catch is that you only see one lender's range, which may not be competitive.

A full remortgage means moving to a new lender. You get the whole market, and the chance to change your term or borrow more, but it is a full application: affordability checks, a valuation, a solicitor, and typically one to three months from application to completion. A slightly better headline rate elsewhere can also be eaten by fees, so compare the total cost over the deal period, not just the rate. Our remortgage calculator does that comparison, fees included, and shows the breakeven point.

A sensible sequence: around six months out, get your lender's product transfer quote (often a few clicks in their app), then shop the open market or speak to a broker. If the outside market beats it meaningfully after fees, start the full application early so it completes on time. If not, take the transfer; there is no prize for switching lenders on principle.

What doing nothing costs, month by month

Here is an illustrative example using made-up but plausible rates; real rates change constantly, so run your own numbers.

Take a £200,000 balance with 20 years remaining. A new two-year deal at 4.5% with a £999 fee costs about £1,265 a month. The same mortgage on a 7% SVR costs about £1,551 a month, £285 more. The deeper cost is interest: in the first month the SVR charges about £417 more in pure interest than the 4.5% deal, and less of your payment clears capital.

Delay compounds it. Three months drifting on the SVR before sorting a deal costs about £1,249 more in interest than three months on the new rate. Stay on the SVR for the whole two years that the deal would have covered and you are roughly £8,900 worse off, even after paying the £999 arrangement fee on the deal you skipped. Every month of inaction has a price tag in the hundreds. You can sanity-check what a rate change does to your own payment with the mortgage repayment calculator.

One honest caveat: a short, deliberate spell on the SVR is occasionally rational, for example if you are about to sell, or rates are falling fast and you want to stay deal-free for a month or two. The expensive version is the accidental drift.

The documents that slow people down

Full remortgage applications mostly stall on paperwork, so gather it in month one of the window:

• Photo ID and proof of address.
• Your last three months of payslips and bank statements, plus your latest P60 if employed.
• If self-employed, usually two to three years of accounts, or SA302 tax calculations with matching tax year overviews from HMRC. These take time to pull together, so start first.
• Your current mortgage statement showing the balance and any early repayment charge dates.
• Three years of address history, and a quick check of your credit report for errors or forgotten missed payments. Fixing a credit file mid-application is what really burns weeks.

Product transfers need far less of this, which is part of their appeal.

If rates fall after you lock

You are rarely trapped. With your existing lender under the charter you can switch to a better like-for-like deal up to the day the new term starts. With a new-lender offer, you can usually walk away before completion, though confirm whether any booking or valuation fees are refundable. Treat an early lock as insurance with a free upgrade clause, not a final commitment.

Common questions

How early can I lock in a new mortgage rate before my fix ends?

Typically three to six months ahead, depending on the lender. Under the Mortgage Charter, signatory lenders (covering most of the UK market) let existing customers lock in a new deal up to six months before the current one ends, and switch to a better like-for-like deal right up until the new term starts.

What happens if I do nothing when my fixed rate ends?

Your lender automatically moves you onto its standard variable rate (SVR), which is usually well above current fixed rates. On a £200,000 mortgage, an illustrative gap between a 4.5% deal and a 7% SVR is about £285 a month in payments and about £417 a month in extra interest at the start.

Is a product transfer better than a full remortgage?

A product transfer (new deal, same lender) is faster, usually skips affordability checks and conveyancing, but limits you to one lender's rates. A full remortgage opens the whole market but takes one to three months and more paperwork. Compare total cost over the deal period including fees, then pick whichever is cheaper for you.

Do I need an affordability check to remortgage?

Usually yes for a full remortgage to a new lender, including income evidence and a credit check. A like-for-like product transfer with your existing lender generally does not require a new affordability assessment, which makes it the easier route if your income has dropped since you took the mortgage.

Can I change my mortgage deal if rates drop after I have locked one in?

Often, yes. Mortgage Charter lenders let you swap to a better like-for-like deal with them right up until your new term starts. If you locked with a new lender, you can usually withdraw before completion, though check whether any booking or valuation fees are non-refundable.

Guidance and education, not regulated financial advice.