Porting Your Mortgage vs. Remortgaging When You Move House in the UK: Which Saves More

Key Takeaway

When you move house before your mortgage deal ends, porting your existing mortgage avoids early repayment charges but locks you into your current rate, while remortgaging lets you access today’s best rates but may trigger exit fees of 1-5% of your loan balance. Porting saves more if your current rate beats the market and your lender approves the new property quickly, but remortgaging typically wins if rates have fallen, your deal is nearly finished, or you need to borrow significantly more.

Introduction

Moving house during a fixed-rate or discount mortgage period forces a choice: port your existing deal to the new property or remortgage onto a fresh product. The right answer depends on your current interest rate, how much early repayment charge (ERC) you face, the new property price, and the rates available today. This guide compares both routes and shows which saves more in common scenarios.

Quick Comparison

Factor	Porting Your Mortgage	Remortgaging When You Move
Early repayment charge	Avoided if you port within the lender’s timeframe (typically 90-180 days)	Usually 1-5% of outstanding balance if you exit mid-deal
Interest rate	Keep your existing rate (good if it is below market)	Access current market rates (may be lower or higher)
Arrangement fee	May pay a fee for additional borrowing	New product fee (often £999-£1,999)
Legal costs	Lender may cover some conveyancing	Borrower typically pays all legal fees
Property approval	Lender must approve the new property and your affordability	Choose any lender willing to lend on the new property
Flexibility	Tied to one lender	Shop across the market for the best deal
Timeline	Must complete within lender’s porting window (strict deadlines)	More flexible timing (can apply earlier)

What Is Porting a Mortgage?

Porting means transferring your existing mortgage deal (the balance, rate, and remaining term) from your current property to your new home. Most lenders allow porting during the deal period, but you must apply, pass a fresh affordability assessment, and complete the move within a narrow window (often 90 to 180 days). If you borrow more to afford the new property, the extra borrowing sits on a separate rate (typically the lender’s current product range), creating a blended rate across the total loan.

According to MoneyHelper, porting can help you avoid early repayment charges, but the lender is not obliged to approve the port (MoneyHelper, 2026). If the new property fails the lender’s valuation or your income no longer supports the loan, the port is declined and you face the ERC anyway.

What Is Remortgaging When You Move?

Remortgaging when you move means repaying your current mortgage (triggering any early repayment charge if you are mid-deal) and taking out a new mortgage with any lender for the new property. You shop the market for the best rate, choose the product (fixed, tracker, or discount), and apply as you would for any remortgage. The new lender orders a valuation, you instruct a conveyancer, and the loan completes on your moving date.

This route gives you full flexibility to switch lenders and access the lowest rates available, but you pay the ERC (if applicable), a new arrangement fee, and legal costs without the partial subsidy some lenders offer for porting customers.

Cost Comparison

Porting costs:

Early repayment charge: £0 (avoided if the port completes in time).
Arrangement fee: often £0 for the ported balance; £999-£1,500 for additional borrowing.
Legal fees: some lenders contribute £250-£500; borrower pays the rest (typically £800-£1,200 total).
Valuation: usually free for the ported amount; may be charged for additional borrowing.

Remortgaging costs:

Early repayment charge: 1-5% of the balance (e.g., £2,500 on a £200,000 loan at 2.5%; declines each year of the deal).
Arrangement fee: £999-£1,999 for the new product.
Legal fees: £800-£1,500 (borrower pays in full).
Valuation: often free if included in the product.

As outlined in foundational texts such as Principles of Finance, borrowers minimize total cost by comparing the present value of interest savings against upfront fees and penalties across the mortgage term.

Example: You have £180,000 outstanding on a five-year fixed rate at 2.8%, with two years remaining and a 3% ERC. Current five-year fixes are 4.2%. Porting avoids the £5,400 ERC and keeps you at 2.8% for two more years (saving roughly £2,520 in interest versus 4.2%), but you lose the chance to lock in a lower rate if the market drops. Remortgaging costs £5,400 upfront but may save more if you find a significantly better deal or plan to overpay aggressively.

When Porting Saves More

Porting typically wins when:

Your existing rate is below the current market (you locked in a 1.9% fix in 2021; today’s equivalents are 4%+).
You have more than 12-18 months left on your deal (the longer the remaining term, the greater the interest saving).
Your ERC is high (4-5% in the early years of a long fix).
You are borrowing only slightly more (additional borrowing is a small portion, so the blended rate stays favourable).
Your lender approves the new property quickly and you can complete within the porting window.

Porting locks in your low rate and avoids a large exit penalty, making it the lower-cost route even after paying a small fee for extra borrowing.

When Remortgaging Saves More

Remortgaging is usually cheaper when:

Current market rates are lower than your existing rate (your deal is 4.5%; new fixes are 3.8%).
You are in the final 6-12 months of your deal (the ERC has tapered to 1% or less, and the interest saving from a better rate exceeds the penalty).
You need to borrow significantly more (porting creates a high blended rate because the new chunk sits on a worse product).
Your lender is slow to approve ports or has strict criteria (you risk missing the window and paying the ERC anyway).
You want product features your current lender does not offer (offset facility, unlimited overpayments, or a longer fix).

Shopping the market gives you access to the most competitive rates and the flexibility to choose the lender and product that match your plans.

Pros and Cons

Porting:

Pros: Avoids ERC, keeps a favourable rate, some lenders subsidise legal costs.
Cons: Tied to one lender, new property must pass their criteria, strict deadlines, blended rate if you borrow more, no guarantee of approval.

Remortgaging:

Pros: Access to best market rates, any lender, flexible timing, full product choice.
Cons: Pay ERC if mid-deal, new arrangement fee, full legal costs, application process from scratch.

Which Option Is Right for You?

Port if: You are more than 18 months into a long fixed deal at a rate well below today’s market, your ERC is over 2%, and you are confident your lender will approve the new property and your affordability within the porting window.

Remortgage if: Rates have fallen since you took your deal, you are within 12 months of the end of your term, you need much more borrowing, or you want the freedom to choose the best product across the market.

Borderline cases: If your ERC is 1-2% and your rate is only marginally better than the market, calculate the total cost of each route (ERC plus fees plus interest over the remaining deal period) or consult a mortgage broker for a side-by-side comparison.

Conclusion

Porting your mortgage saves more when your current rate is a bargain and your ERC is high, while remortgaging wins when rates have improved or you are near the end of your deal. Check your lender’s porting terms, compare today’s rates, and factor in all fees before deciding. For personalised advice on your situation, speak to an FCA-authorised mortgage adviser.

Your home may be repossessed if you do not keep up repayments on your mortgage. Rates, fees, and porting criteria vary by lender and change frequently. This article provides general educational information only and is not regulated mortgage advice, financial advice, or legal advice. Refisage is not authorised by the Financial Conduct Authority. For advice tailored to your circumstances, consult an FCA-authorised mortgage adviser or visit MoneyHelper for impartial guidance.