Porting a mortgage means taking your existing mortgage product, usually its interest rate and remaining deal period, to a new property when you move home.

It does not mean your current mortgage simply moves across automatically. In most cases, your existing mortgage is repaid when you sell, and your lender considers a new mortgage application on the property you are buying. If approved, the product benefit is carried over to the new mortgage.

In plain English: a mortgage can be portable in principle, but you still need to qualify at the time you move.

That usually means your lender will look again at your income, outgoings, credit profile, deposit, loan-to-value, the new property and the amount you want to borrow. If you need extra borrowing, that extra amount may be on a different product and rate from the part you port.

This guide explains what porting a mortgage means in practice, when it can help, when it can be awkward, and what to check before you commit to a sale or purchase.

This is general guidance only and is not personal mortgage advice. Your options depend on your circumstances, lender criteria and the property involved.

What does porting a mortgage mean in practice?

Porting a mortgage means applying to your current lender to move your existing mortgage product to a new property.

The important word is product. You are usually trying to keep the deal you already have, such as a fixed rate, tracker rate or discounted rate, rather than physically transferring the old mortgage without checks.

A typical porting process looks like this:

The product may be portable, but the application can still be declined if the lender is not satisfied with affordability, credit history, loan-to-value or the new property.

Is porting a mortgage a good idea?

Porting can be a good idea where it genuinely improves the overall cost and keeps your move workable. It is not automatically the best route just because the mortgage says it is portable.

Porting is often worth exploring if:

• you are still inside a fixed, tracker or discounted deal;
• your current rate is lower than new deals available to you;
• redeeming the mortgage would trigger an early repayment charge;
• your income and credit profile still fit your lender’s criteria;
• the new property is likely to be acceptable to your lender;
• you want to move before your current deal ends.

It may be less attractive if:

• your lender’s new borrowing rate is high;
• you need significant extra borrowing;
• your income has reduced or become more complex;
• your credit position has changed;
• the property is unusual or harder to mortgage;
• the port creates multiple mortgage parts with different end dates;
• another lender offers a better overall route after fees, charges and flexibility are considered.

public guidance explains that borrowers should think carefully about the full cost of buying and owning a home, not just the headline mortgage payment. GOV.UK’s home-buying guidance also reminds buyers to budget for costs such as legal fees, surveys, valuation fees, mortgage fees and Stamp Duty Land Tax where applicable.

So the question is not simply “can I port?” The better question is:

Does porting still make sense after the rate, early repayment charge, fees, new borrowing cost, timing and future flexibility are all considered?

Is porting better than taking a new mortgage?

Sometimes. The answer depends on the numbers and the lender fit.

A lower existing rate can be valuable, but it does not settle the decision by itself. You also need to compare:

• any early repayment charge;
• arrangement or product fees;
• valuation and legal costs;
• the rate on any additional borrowing;
• whether the mortgage parts end at different times;
• whether you may want to move, overpay or remortgage again soon;
• whether the lender will accept your income and the property.

The Bank of England explains that Bank Rate influences wider borrowing and savings rates in the economy. Mortgage pricing is not the same thing as Bank Rate, but the wider interest-rate environment can affect the products available when you move.

If you are unsure, a broker can compare porting with the cost of leaving your current lender and taking a different mortgage. That comparison should include charges and fees, not just the monthly payment.

Who is porting a mortgage relevant for?

Porting is most relevant if you are selling your current home and buying another property before your existing mortgage deal ends.

It can apply if you are:

• moving to a more expensive home;
• moving to a cheaper home;
• borrowing the same amount;
• increasing your mortgage;
• reducing your mortgage;
• changing the mortgage term;
• trying to avoid an early repayment charge;
• trying to keep a favourable existing rate.

For example, someone who fixed their mortgage at a lower rate may be reluctant to give up that deal when moving. Porting could allow them to keep the old rate on some or all of the borrowing, subject to the lender’s rules.

But porting is not only a rate question. It is also an affordability, property and timing question. If any of those parts do not work, the lender may not approve the port even if the product is portable.

What can make porting harder?

Porting can become harder when your circumstances or the property have changed since the original mortgage was agreed.

Common issues include:

• lower income than when you first borrowed;
• a recent job change;
• moving from employment to self-employment;
• variable income from bonus, overtime or commission;
• contractor income;
• maternity, paternity or parental leave;
• new loans, car finance or credit card balances;
• missed or late payments;
• a higher loan-to-value;
• needing significantly more borrowing;
• a property with unusual construction, condition or title issues;
• short lease concerns;
• tight completion deadlines;
• a long or uncertain property chain.

Lenders assess the new property because it is their security for the mortgage. A property can be harder to mortgage if there are concerns about construction type, condition, lease length, legal title, valuation or future marketability. GOV.UK has guidance on leasehold property, which is worth reading if the property is leasehold.

Criteria can also change. A lender that accepted your situation several years ago may apply different rules now. That does not mean porting cannot work, but it does mean you should avoid relying on assumptions.

How do lenders assess a porting application?

Lenders commonly consider:

• your income;
• your regular outgoings;
• credit commitments;
• dependants and household costs;
• credit history;
• deposit and equity;
• loan-to-value;
• property type and valuation;
• mortgage term and age at the end of the term;
• whether the existing product rules allow the proposed port;
• whether you are borrowing more, less or the same amount.

public guidance’s mortgage guidance encourages borrowers to think about what they can afford, not just what they may be able to borrow. The FCA’s consumer information also stresses the importance of understanding regulated financial products and getting suitable help where needed.

Your loan-to-value, often shortened to LTV, is the mortgage amount compared with the property value. For example, if you buy for £400,000 and borrow £300,000, the LTV is 75%. LTV can affect whether a lender is comfortable with the case and which products may be available.

The lender will also normally require a valuation. If the valuation is lower than expected, the loan-to-value may increase and the lender may reduce the maximum loan, change the product available or decline the case.

What happens if you need to borrow more?

If you move to a more expensive property, you may need a larger mortgage. Many borrowers assume the whole mortgage stays on the old rate, but this is not always how it works.

A common structure is:

The additional borrowing may have:

• a different interest rate;
• a separate product fee;
• a different end date;
• a different early repayment charge period;
• different overpayment rules.

This can still be a sensible route, but it needs careful planning. If one part of the mortgage ends in 2027 and another ends in 2029, future remortgaging may be less tidy. You may have to decide whether to switch one part early, let one part move to a reversion rate, or wait until both parts can be aligned. The right answer depends on costs and timing at that point.

Example scenario: keeping the old rate, but needing extra borrowing

A homeowner is part-way through a fixed-rate deal and wants to move to a larger property. Their current mortgage product is portable, so they assume the move is straightforward: keep the existing rate, borrow the extra amount needed, and avoid paying an early repayment charge.

The practical issue is that the lender does not just “move the mortgage across”. The existing product may be portable on the current balance, but the extra borrowing is assessed under today’s rules. Since the original mortgage was agreed, the household has taken on car finance, childcare costs have increased, and one applicant’s income now includes more variable bonus. The lender may treat that income cautiously and include the car finance in affordability.

The result is that the ported part could still look attractive, while the overall application becomes tight because of the additional borrowing.

Key checks before relying on this route would include:

The lesson is that porting can be useful, but the extra borrowing often decides whether the plan really works.

What happens if you downsize or borrow less?

If you move to a cheaper property, you may need a smaller mortgage than you have now.

For example:

Your lender may allow you to port £180,000 of the existing product, but the remaining £70,000 is repaid from the sale proceeds. Whether an early repayment charge applies to that repaid amount depends on your product terms and lender rules.

This is one of the easiest places to make a mistake. A borrower may focus on keeping the rate, but miss the charge for reducing the balance. Check the early repayment charge calculation before committing to the move.

public guidance has guidance on paying off your mortgage early, including the need to understand charges and product terms.

How long does porting a mortgage take?

There is no single timescale that applies to every case. A straightforward port can be quicker than a complex one, but it still needs underwriting, valuation and legal work.

The timing can be affected by:

• how quickly you provide documents;
• whether your income is simple or complex;
• whether the lender needs more information;
• valuation availability;
• property issues raised by the valuer or solicitor;
• chain delays;
• whether you need extra borrowing;
• whether the lender’s porting window has specific deadlines.

As a practical rule, check portability and affordability before you rely on the port when making an offer. Do not wait until the chain is under pressure if your plan depends on keeping the existing product or avoiding an early repayment charge.

For wider timing context, read our guide on how long it takes to get a mortgage.

What could porting look like in real situations?

These scenarios show why “portable” does not mean “simple”. Porting is a lender application linked to a property transaction, so the weakest part of the case can affect the whole plan.

Which mistakes cause problems?

The biggest mistake is assuming that a portable product gives you an automatic right to move the mortgage.

Other common mistakes include:

Assuming the old mortgage simply transfers

The old mortgage is usually repaid on sale. The lender then considers a new mortgage on the new property and applies the portable product if its rules are met.

Checking too late

If you only ask about porting after your offer is accepted, you may find that affordability, property type or timing creates a problem. Check early if the port is important to your move.

Ignoring the cost of extra borrowing

If you need more money, the additional borrowing may be on a current product at a different rate. The blended cost may be higher than expected.

Missing early repayment charges

Charges can still matter if you repay some or all of the mortgage, complete outside the lender’s porting rules, or decide to move to another lender.

Overlooking product end dates

Porting plus extra borrowing can create two or more mortgage parts. Different end dates can make future switching or remortgaging more complicated.

Comparing only the interest rate

The rate matters, but the full comparison should include fees, early repayment charges, valuation costs, legal costs, flexibility, term and your future plans.

Not checking the property properly

Some properties are more difficult to mortgage. If the lender dislikes the property after valuation or legal review, the port may not proceed even if your income fits.

What documents should you prepare before asking about porting?

The cleaner your information, the easier it is to assess whether porting is realistic.

Prepare:

• your latest mortgage statement;
• your current mortgage offer or product details;
• the interest rate, deal end date and early repayment charge details;
• your estimated property value and expected sale price;
• the purchase price of the new property;
• your expected deposit and equity;
• the amount you want to borrow;
• details of any extra borrowing and its purpose;
• recent payslips if employed;
• accounts, tax calculations and tax year overviews if self-employed;
• bank statements;
• details of loans, credit cards, car finance and other commitments;
• information on the new property, including tenure and lease length if leasehold;
• your target completion timescale;
• any chain deadlines.

If you are self-employed, make sure your tax and income evidence is up to date. GOV.UK has information on Self Assessment tax returns.

What should you ask your lender or broker?

Before committing to porting, ask:

• Is my current product portable?
• What is the deadline or time window for porting?
• Can I port the full balance, or only part of it?
• What happens if I borrow more?
• What rate applies to the additional borrowing?
• Will the mortgage have multiple parts and end dates?
• What early repayment charge applies if I repay some or all of the current mortgage?
• What fees apply?
• What income evidence will be needed?
• Is the new property likely to be acceptable?
• What happens if the valuation is lower than expected?
• What is the fallback if the lender declines the application?

A good porting decision usually has a fallback plan. A one-lender plan can be fragile if the valuation, affordability assessment or product rules do not work as expected.

When should you speak to a broker?

You may not need a broker for a very simple port where your lender has already confirmed the product is portable, you are borrowing the same amount or less, your income and credit position are stable, and the property is standard.

A broker can be more useful where:

• you need to borrow more;
• your income has changed;
• you are self-employed or a contractor;
• your credit file has changed;
• the property is unusual;
• you are downsizing and repaying part of the mortgage;
• your chain has tight deadlines;
• you want to compare porting with paying an early repayment charge and using another lender;
• you are unsure whether your current lender’s route is the best overall option.

A broker can help compare:

• staying with your current lender and porting;
• porting with additional borrowing;
• taking a new mortgage elsewhere;
• waiting until your current deal ends;
• changing the purchase price, deposit or mortgage term;
• using a different structure if the first route does not fit.

We cannot promise a lender will approve an application, offer a particular rate or deliver a specific outcome. But we can help you test the options before you make decisions around the sale, purchase or early repayment charge.

If you are planning a move and want to understand whether porting is worth exploring, you can speak to a mortgage adviser or make a finance enquiry.

What should you read next?

• Mortgage with no early repayment charge
• How long does it take to get a mortgage?
• Quick guide to UK mortgage types
• What is an offset mortgage?
• Buying another property with a second mortgage
• Finance hurdles in UK property
• What is a lock-in agreement?
• Buying property in a limited company vs personal name
• 7 reasons to use a property search agent
• Retirement interest-only mortgage

FAQs

What does porting a mortgage mean?

It means applying to move your existing mortgage product to a new property when you move home. You are usually trying to keep the current rate and deal terms, subject to your lender’s approval.

Does porting mean the mortgage automatically transfers?

No. You normally need a new mortgage application, affordability assessment, credit checks, valuation and lender approval.

Can I port my mortgage and borrow more?

Possibly. If your lender agrees, you may be able to keep the existing product on the current balance and take extra borrowing on a new product. The extra borrowing may have a different rate, fee and end date.

Can I port if I am downsizing?

Possibly. You may be able to port a smaller balance, but repaying part of the mortgage could trigger an early repayment charge depending on the product rules.

Is porting always cheaper than a new mortgage?

No. Porting can reduce costs in some cases, especially where an existing rate is favourable or an early repayment charge is high. But you still need to compare the full cost, including fees, charges, extra borrowing rates and future flexibility.

Can a lender refuse to port my mortgage?

Yes. A lender may refuse if you no longer meet affordability or credit criteria, if the property is not acceptable, if the loan-to-value is too high, or if the product rules do not support the proposed port.

How long does porting take?

Timescales vary. A straightforward case may be faster than a complex one, but underwriting, valuation, documents, legal work and chain delays can all affect timing. Check early if your move depends on porting.

Should I speak to my lender or a broker first?

You can ask your lender whether the product is portable, but a broker can help compare porting with other options. This can be useful if you need extra borrowing, have changed circumstances or want to understand the total cost.