If your fixed, discounted or tracker mortgage deal is approaching its end, starting early can give you time to compare options without drifting onto a potentially less suitable follow-on rate. This guide explains when to remortgage in the UK, how to build a realistic comparison, which documents and costs to check, and when to revisit the decision.
Overview
There is no single best time to remortgage. The right point depends on your deal’s end date, any early repayment charge (ERC), your remaining balance, property value, income and the mortgage products available when you apply.
As a practical rule, begin reviewing your position several months before the current deal ends. This gives you time to:
- Confirm the exact end date and the date any ERC reduces or disappears.
- Check what rate you will move to if you take no action.
- Estimate your current loan-to-value (LTV) band.
- Compare a new deal with a product transfer from your existing lender.
- Gather documents and resolve affordability or credit-file issues.
- Allow for valuation, legal, broker and product fees where relevant.
Remortgaging means replacing your existing mortgage, usually with a new deal from another lender. A product transfer is a new deal with your current lender. A product transfer may involve less paperwork and fewer legal steps, but it should still be compared on total cost and suitability rather than headline interest rate alone.
If your mortgage is on a variable, tracker or standard variable rate, there may be less benefit in waiting for a fixed deal to expire. Review the terms promptly, but check whether leaving early creates an ERC or other charge.
How to estimate the best time to remortgage
Use this simple timeline as a planning framework. Your lender’s terms and the chosen product’s conditions take priority.
About six months before the deal ends
Locate your latest mortgage statement and note the balance, interest rate, repayment type and deal expiry date. Ask your lender when you can secure a future deal and whether an ERC applies before the current deal ends. Some lenders allow applications well in advance, while others use different booking windows, so confirm the process rather than relying on a general rule.
Also check your likely LTV. Divide the outstanding mortgage by a realistic current property value and multiply by 100:
LTV (%) = mortgage balance ÷ property value × 100
A lower LTV can open different product ranges, but do not assume an optimistic valuation. Look at recent comparable sales and the condition of your property. A lender’s valuation may not match an online estimate.
About three to four months before expiry
Start comparing replacement deals and request an agreement in principle only if it is useful for your circumstances. Compare the interest rate, initial period, follow-on rate, fees, ERC structure, overpayment rules and portability. If your income, debts or household circumstances have changed, an independent affordability review may be particularly useful.
About six to eight weeks before expiry
Choose the most suitable route and submit the application if you are changing lender. Prepare proof of income, bank statements, identification, details of existing credit commitments and evidence of deposit or savings where requested. A lender may also require information about leasehold charges, buildings insurance or the property’s construction.
Before the current deal ends
Check that the new mortgage is ready to complete and that the solicitor or conveyancer has received the necessary instructions. Ask for confirmation of the completion date, redemption figure and all fees. If a new deal cannot complete in time, understand which rate will apply temporarily and whether you can still change products later.
Inputs and assumptions for a remortgage comparison
A useful comparison should show both the monthly payment and the cost over the initial deal period. Record these inputs for each option:
- Mortgage balance: use the lender’s current redemption figure where possible, not just an old statement.
- Remaining term: extending the term can reduce the monthly payment but may increase total interest.
- Interest rate: record whether it is fixed, tracker, discounted or variable.
- Initial deal length: compare like with like where practical.
- Product fee: include it in the comparison even if it can be added to the loan.
- Other costs: include legal work, valuation, broker fees, administration charges and any ERC.
- Future rate: for a tracker or discounted deal, calculate more than one rate scenario rather than treating today’s payment as guaranteed.
- Property value and LTV: use a defensible estimate and test what happens if the valuation is lower.
For a basic comparison, calculate:
Initial-period cost = monthly payments during the deal period + fees − incentives
This is not a full personal recommendation. It also does not capture every tax, insurance, maintenance or household-budget issue. Ask the lender or adviser how fees are treated and whether adding a fee to the mortgage will itself attract interest.
Check the affordability of the payment after the initial deal ends. A low introductory payment can be misleading if the follow-on rate is substantially higher or if the term changes. Keep an emergency buffer rather than using every available pound to reduce the balance or pay fees.
Worked examples
The figures below are illustrations only and are not current market quotes. They show how to compare options using the same assumptions.
Example 1: lower rate, higher fee
Assume a borrower has a balance of £180,000 with 20 years remaining. Deal A has a lower initial rate but a £1,000 product fee. Deal B has a slightly higher rate and no product fee. If Deal A reduces the payment by £45 a month for a two-year initial period, its payment saving is £1,080. After allowing for the £1,000 fee, the apparent advantage is £80 before any other costs. The borrower should then compare the likely follow-on rate, overpayment rules and the cost of arranging the next deal.
Example 2: changing the term
Suppose the same balance is refinanced over 25 years instead of 20. The monthly payment may fall, but the mortgage remains outstanding for longer and may generate more interest overall. A fair comparison should therefore show both the monthly payment and the total interest under each term. If affordability permits, keeping the original term or making controlled overpayments may produce a different long-term result, subject to the lender’s limits and charges.
Example 3: product transfer versus changing lender
An existing lender offers a straightforward product transfer with no legal work, while a new lender offers a lower rate but charges a product fee and requires a full application. Add all costs to the first-period comparison. Also consider whether the new lender’s valuation, underwriting and completion timetable could create a temporary period on the old lender’s follow-on rate.
When to recalculate and what to do next
Revisit your remortgage calculation whenever a key input changes. This includes a change in mortgage balance, property value, income, employment, household spending, credit commitments or lender pricing. Recalculate if your deal expiry date changes, you receive a new product illustration, an ERC becomes payable or a valuation places you in a different LTV band.
Use this checklist:
- Write down the deal end date, current balance, term and ERC dates.
- Request a redemption figure and ask your lender about product-transfer options.
- Estimate your LTV conservatively.
- Compare at least one existing-lender option with relevant alternatives.
- Calculate payments, fees and initial-period cost together.
- Stress-test the payment if rates, income or essential costs move against you.
- Check the follow-on rate, overpayment rules and exit charges.
- Keep copies of the mortgage illustration and confirm completion arrangements.
Start early, but do not treat an early quote as permanent. Mortgage pricing, lender criteria and your own circumstances can change before completion. If the decision is complex, seek regulated mortgage advice and ask how the adviser is paid. Rechecking the figures during an annual mortgage review can also help you avoid an automatic move to an unsuitable rate.
