Stay here for the switch calculation
Compare leaving early, waiting until expiry, fallback-rate risk, fees and the selected decision window.
Stay here for the switch calculation → Remortgage Calculator
Remortgage calculator for early-switch and post-expiry decisions
Compare two common remortgage decisions: leaving your current deal early, or comparing the post-expiry fallback rate with a replacement deal over the same planning window.
Window-based remortgage plannerWhole-term totals avoidedSwitch-cost logic kept explicit
Start Window
Many borrowers start speaking to a lender around 6 months before expiry
Fallback Risk
Many fixed deals move onto the lender's SVR if no action is taken
Cost Warning
Remortgaging can cost more than £1,000 once fees are included
Calculator
Choose the comparison window that matches your actual remortgage decision
Use the leave-early tab if you are still inside the current deal and want to test whether an ERC could be worth paying. Use the after-deal tab if you are comparing a fallback rate after expiry with a replacement deal.
Current Mortgage
£
£
%
years
months
This drives the early-exit comparison window.
Replacement Deal
%
years
Keep this equal to the remaining term for the cleanest like-for-like comparison.
£
£
Charged by the current lender if you leave before the deal ends.
£
£
How to use this comparison
Use this tab for the "should I pay an ERC and switch before my current deal expires?" question. It compares the remaining months on your current deal only rather than projecting the whole mortgage life.
Stay on Current Deal
Monthly Payment
£1,375.77Interest During 1 year
£10,859Balance At Natural Deal End
£194,350Switch Now
Monthly Payment
£1,297.91Interest During 1 year
£9,467Upfront Switching Costs
£1,499Balance At Natural Deal End
£193,892Early-Switch Summary
Monthly Payment Difference
+£77.86Positive means switching now reduces the monthly payment.
Interest Difference Over 1 year
+£1,392Positive means switching now cuts interest during the remaining current-deal window.
Net Cash Difference After Switching Costs
-£565Positive means the payment reduction over the remaining current-deal window exceeds the upfront switching cost.
Balance Difference At Natural Deal End
+£458Positive means switching now leaves you owing less when your current deal would have ended.
Current LTV
57.14%This is a useful reference for how the case may be priced, but it is not a lender quote.
Breakeven timing
At the current monthly payment gap, it would take about 1 year 8 months to recover the upfront switching cost.
Interpret with care if the term changes
If the new term is longer than the current remaining term, a lower monthly payment can simply reflect slower repayment. That is why this planner also shows interest during the window and the balance left at the natural deal-end checkpoint.
Switch Route
Separate early switching, deal expiry and lender research before comparing rates
The remortgage planner owns the switch-or-stay calculation. If the job is rate structure, lender selection or deadline planning, use the adjacent support page first and return here when the numbers are ready.
Move to the remortgaging guide for process
Read the guide when the question is same lender versus new lender, legal work, valuation, documents or adviser checks.
Move to the remortgaging guide for process →Move to the lender hub for route selection
Use the hub when the query is about a specific lender, retention route, existing-customer switch or lender fee.
Move to the lender hub for route selection →Move to the rate planner for structure
Use the interest-rate planner when the question is fixed, tracker, discount, SVR or a rate-change pressure test.
Move to the rate planner for structure →Use Cases
Why the planner now splits early-switch and post-expiry decisions
These are different mortgage questions, so compare them separately.
Leave early if the current deal still has months left
This window compares the months that remain on the current deal only. That keeps the ERC question focused on the period it actually affects.
Compare fallback versus replacement after the deal ends
Many borrowers move onto their lender's SVR if they do nothing. The second tab lets you compare that fallback path with a replacement deal over a selected post-expiry window.
Keep fees and balance movement visible
A remortgage can look cheaper simply because the term is being stretched. That is why this planner shows upfront switching costs, interest during the selected window and the balance left at the end.
Interpretation
What to watch when fees, terms or deal structures differ
These are the points that most often distort a remortgage comparison.
A longer term can create an artificial monthly saving
If the replacement deal stretches the repayment period, the monthly payment may fall even if the mortgage is not cheaper in any meaningful sense. That is why the planner also shows interest during the window and the balance still owed.
Switching costs should never disappear into the headline rate
Product fees, valuation costs, legal costs and any early repayment charge are kept on-page so the route does not repeat the common mistake of comparing only the rate.
The result is only as good as the fallback rate you enter
For the after-deal comparison, use the rate your lender has actually shown you if you have it. Do not fill that gap with a guessed market average.
ERC And Overpayments
Check the charge before you treat a lower rate as a saving
The leave-early decision often overlaps with overpayment and fee questions. Keep those costs separate before you rely on the remortgage result.
ERC first when the deal is still active
If the current product has a charge period left, estimate the early repayment charge before comparing the replacement deal.
Overpayment next when cash is the trigger
If the switch is partly driven by a lump sum or a plan to reduce the balance, compare that cash in the overpayment calculator as well.
Fees last before deciding
Product fees, legal work, valuation costs and any exit fee should sit beside the ERC rather than disappear into the rate comparison.
Tracking
Track the end date locally if your next decision depends on timing
Timing is often the biggest avoidable remortgage mistake, so it helps to keep the deal end date visible.
Mortgage Journal
Store your deal end date locally in your browser and surface 6, 3 and 1 month reminders based on the date you enter.
Mortgage Deal Ending
Use the action-plan page if your deal expiry date is now the main priority.
Remortgaging Guide
Read the process guide when same-lender and switch-lender routes need separating.
Remortgage 2026 Guide
Place the calculator result inside the current remortgage timing and support context.
Lender Hub
Compare lender-specific switch windows, retention paths and fee questions before choosing a route.
ERC Calculator
Estimate the early repayment charge before judging whether leaving the current deal early is worth it.
ERC Guide
Check allowance, exit-fee and redemption-figure wording before treating the charge as final.
Fees Planner
Check product fees, legal costs and valuation costs separately before trusting a lower rate headline.
Interest Rate Planner
Compare the rate structure itself if you are still deciding between fixed and variable options.
Frequently Asked Questions
Does this calculator tell me how much I will save over the whole mortgage term?
No. It compares selected planning windows only. A remortgage decision depends on the rate, the fee, the deal length and what happens next, not on a fixed whole-term answer.
When should I start remortgaging if my deal is ending soon?
You can often start talking to your lender around six months before your current deal ends.
What happens if I do nothing when my fixed deal ends?
Many borrowers move onto their lender's standard variable rate if they take no action when the fixed period ends.
What does the leave-early tab compare?
It compares the remaining months on your current deal only. It is for the question of whether paying the early repayment charge to switch before expiry could make sense on the numbers you enter.
What does the after-deal tab compare?
It compares the selected post-expiry window only. Enter the rate you would fall onto if you did nothing, then compare it with a replacement deal over the same window.