Heron Financial preserved a 1.89% fixed rate by porting the clients’ existing TSB mortgage to a new £835,000 detached home, with £200,000 of borrowing carried over and a £635,000 deposit funded from the sale of their previous property. The case completed in August 2025 after Heron Financial worked through three specific challenges: a tightening porting window, an EPC exemption that required formal evidence, and a solicitor query about which charges from the original mortgage needed redeeming. The clients moved into their new home with their sub-2% rate intact.
The clients
The clients were a couple, both self-employed limted company directors, buying a detached family home for £835,000. They had sold their previous property earlier in the year for £635,000, which provided the deposit, and wanted to bring their existing TSB mortgage with them rather than redeem it and take out a new product at current rates. With their original fixed rate set at 1.89%, the financial difference between porting and starting fresh was substantial.
The case at a glance
- Buyers: Joint applicants, both self-employed Ltd company directors
- Property type: Detached house
- Purchase price: £835,000
- Deposit: £635,000 from sale of the previous property (~76%)
- Loan amount: £200,000 (ported)
- LTV: Approximately 24%
- Lender: TSB Bank
- Product: Ported original fixed rate at 1.89%
- Repayment method: Capital and interest (assumed; to confirm)
- Outcome: Mortgage offer issued in June 2025; case completed in August 2025
Why this case mattered
Porting allows a borrower to take their existing mortgage product to a new property, keeping the rate they already have rather than redeeming and applying for new lending at whatever rates are available now. Where the original rate is materially below current market pricing, that distinction can be worth tens of thousands of pounds across the remaining term of the fixed deal.
In this case, the 1.89% original rate was well below mainstream rates available in 2025. Preserving it through porting was the financial centre of the case. Three issues threatened to derail it.
1. Porting timing. Lenders typically allow a window of three to six months between the sale of the old property and the purchase of the new one for porting to be possible. The clients had sold in January, and by June the case was at the outer edge of TSB’s tolerance. There was a real risk the application would need to be resubmitted or treated as a new loan at current rates.
2. EPC exemption evidence. The new security property was exempt from the standard Energy Performance Certificate requirement, but the exemption needed to be formally applied for and properly evidenced before the lender would proceed. EPC exemptions usually apply to listed buildings, places of worship, certain temporary buildings or properties with specific exemption grounds. Without satisfactory evidence, the lender would not progress the offer.
3. Charges and redemption confusion. Once the offer was issued, the clients’ solicitor flagged that the offer wording wasn’t fully specific about which charges from the original mortgage needed to be repaid against the security being released. Without clarification, the conveyancing process could stall on the day of completion.
How Heron Financial approached the recommendation
Heron Financial managed each issue in turn.
On porting timing, the Heron team kept TSB engaged through the lengthening gap and worked with the client to maintain momentum on the property purchase. The case held together within TSB’s process and the offer was issued in June 2025.
On the EPC exemption, Heron Financial chased the evidence trail, ensured the formal exemption application was in place, and presented the evidence to TSB in the form the lender required.
On the charges and redemption query from the solicitor, Heron Financial directed the solicitor to TSB’s post-offer team to clarify the charge position, rather than leaving the solicitor to interpret the offer wording in isolation. The right team at the right point in the process resolved the query quickly.
The outcome
The formal mortgage offer was issued in June 2025. With the EPC exemption evidenced and the charge position clarified, the case progressed through to completion in August 2025. The clients moved into their new home with their original 1.89% fixed rate intact, carried across to the new property under TSB’s porting process.
What this means for buyers in a similar position
Porting is one of the most valuable and most under-discussed features of a UK mortgage. For borrowers with rates below current market levels, porting can save tens of thousands of pounds across the remainder of the fixed term. But porting is not automatic, and several things commonly trip cases up.
Timing windows. Most lenders require the old property sale and the new property purchase to complete within a defined window, typically three to six months. Borrowers who sell first and then take time to find a new property can find the window closing on them. Affordability reassessment. Porting still requires the lender to reassess affordability at current criteria, which can trip up borrowers whose income has changed since the original mortgage or whose new property is more expensive (and therefore needs additional borrowing on top of the ported amount).
Property criteria. The new security property has to meet the lender’s criteria, which can include EPC requirements, valuation, lease length on flats, building type and other factors.
Process complexity. Porting cases often involve more moving parts than a clean purchase or remortgage, particularly where there are second charges, related sales or unusual property features. Working with a broker who knows how each lender’s porting process works is what keeps the case on track.
For self-employed Ltd company directors, porting can be particularly worthwhile because applying for new lending at current rates means going through full self-employed underwriting again, which is more involved than for PAYE borrowers. Preserving the existing arrangement is often the smoother route.
FAQs
What is mortgage porting?
Mortgage porting is a feature offered by some UK lenders that allows a borrower to take their existing mortgage product to a new property when they move. The original rate, fixed term and other terms continue on the new property rather than being redeemed and replaced with a new product at current rates.
How long after selling can I port a mortgage?
Most lenders allow a window of three to six months between the sale of the old property and the purchase of the new one for porting. The exact window varies by lender. In this Heron Financial case, the gap between sale and purchase stretched close to TSB’s tolerance and the case was managed carefully to stay within the porting process.
Is porting always cheaper than a new mortgage?
Not always, but often. Where the original rate is materially below current market pricing, as in this Heron Financial case at 1.89%, porting can preserve a substantial saving across the remainder of the fixed term. Where the original rate is similar to or higher than current rates, redeeming and remortgaging may be the better option.
Can self-employed Ltd company directors port a mortgage?
Yes. The lender will reassess affordability against current criteria, but the porting itself is available. In this Heron Financial case, joint applicants who were both self-employed Ltd company directors successfully ported their TSB mortgage to a new £835,000 home.
What happens if my new property requires an EPC exemption?
EPC exemptions apply to certain property types, including listed buildings and properties with specific exemption grounds. The exemption typically needs to be formally applied for and evidenced before the lender will proceed. In this Heron Financial case, the EPC exemption evidence was a specific work item that needed managing through the lender’s process before the offer could be issued.
Why might a solicitor need to speak to the lender's post-offer team during porting?
Porting cases can involve specific charges, redemption arrangements and security adjustments that the standard offer wording doesn’t always make explicit. The lender’s post-offer team is set up to clarify these queries directly, which keeps the conveyancing on track. In this Heron Financial case, Heron Financial directed the solicitor to TSB’s post-offer team to clarify the charge position, which resolved the query and let completion proceed.
