Porting your mortgage when you move home in Cardiff
Quick answer: Porting means taking your existing mortgage deal — the rate and terms — with you to the home you're buying, instead of paying an early repayment charge to leave it. Two things surprise people: it's the deal that moves, not the loan, so you go through a full new application with the same lender; and if the new home needs a bigger mortgage, the extra is a second product at today's rates, not more of your old one. Porting usually wins while you're inside a fixed period with an ERC — and often doesn't once the fix has ended.
What porting actually is
Most fixed and tracker mortgages sold in the UK are "portable", and the word makes the process sound simpler than it is. What transfers to the new property is your product: the interest rate, the remaining fixed period, and the terms that came with it. What does not transfer automatically is the lending decision.
Porting is a new mortgage application with your current lender, against the new property, at your current circumstances. The lender values the new home, re-checks your income and outgoings under today's criteria, and can say no — even though they already lend to you. If they do say yes, your old deal carries on against the new address, and no early repayment charge is due on the amount you port.
When porting beats a new mortgage — and when it doesn't
The decision usually comes down to two questions: is there an ERC to avoid, and is your existing rate better than today's market?
| Situation | Usually better | Why |
|---|---|---|
| Inside a fixed period, ERC applies, your rate is below today's | Port | Keeps the cheap rate and avoids an ERC of typically 1–5% of the balance |
| Inside a fix, but today's rates are lower than yours | Run both numbers | Paying the ERC to take a cheaper new deal can win — only the arithmetic on your actual figures settles it |
| Fix has ended (or ends around your moving date) | New mortgage | Nothing to port that's worth keeping — you're free to shop the whole market |
| Your lender declines the port | New mortgage | A different lender may read your circumstances differently — a decline from one is not a decline from all |
The same total-cost habit from our remortgaging in Cardiff guide applies here: compare monthly payment × months plus fees and any ERC across the realistic options, not headline rates.
Moving up: the top-up slice
Cardiff's typical move — flat or terrace to a semi — usually needs a bigger mortgage, and this is where ported mortgages get their characteristic two-part shape:
- Your ported balance stays on the old rate and old end date.
- The extra borrowing goes on a separate product from the same lender's current range, at today's rates, with its own fixed period.
Two practical consequences. First, your blended monthly cost sits between the two rates — a cheap ported slice doesn't make the whole loan cheap. Second, the two slices' fixed periods usually end on different dates, which can leave one part free while the other still carries an ERC. Where you can, pick a top-up product whose end date matches (or lands close to) the ported deal's — future-you, trying to remortgage the whole lot cleanly, will be glad.
Moving down, or porting less
Porting only part of the balance — common when downsizing or when a strong sale price cuts the mortgage you need — usually triggers the ERC on the portion you repay, though not on the amount you port. Some lenders waive or refund an ERC if you complete the new purchase within a set window of redeeming the old loan; windows and conditions vary by lender, so check your mortgage offer's porting wording rather than assuming.
The affordability catch
The port fails most often not on the property but on the re-check. Circumstances that have changed since the original mortgage — a move into self-employment or contracting, a new job in probation, parental leave, credit issues picked up since, or simply criteria the lender has tightened — are all assessed fresh. Passing the original application years ago earns you nothing.
If your own lender declines, that is a data point, not a verdict: affordability differs meaningfully between lenders on identical facts (it's the entire premise of our affordability check), and a port declined at one lender often completes as a new mortgage at another — with the ERC arithmetic folded into the comparison.
Timing: ports move at the speed of your chain
A port completes when your sale and purchase do, so it inherits every timing risk of a Cardiff chain. Points worth planning around:
- Most lenders expect the sale and purchase to complete together or close together; a long gap between selling and buying can turn a port into a redeem-now, reapply-later situation — with the ERC in between.
- A mortgage offer (ported or not) typically lasts around six months; a new-build with a distant completion date can outrun it.
- If you're selling a leasehold flat in the Bay or city centre, the leasehold paperwork adds time on the sale side of the chain, not just the purchase.
The Welsh costs of the move itself
Porting saves the ERC — it doesn't touch the costs of moving:
- Land Transaction Tax on the purchase, with nothing to pay below £225,000 and 6% above it at main rates — the average Cardiff home at £273,079 (May 2026, UK House Price Index) carries a bill of roughly £2,900. Get your exact figure from the stamp duty Wales calculator.
- Higher LTT rates apply if you complete the purchase while still owning your previous home — the second-homes and buy-to-let LTT guide covers how the surcharge and the refund-on-later-sale rules work.
- Valuation, legal work on both transactions, and moving costs are unchanged by porting.
FAQ
Can I port my mortgage to a more expensive house?
Usually, if the affordability re-check supports the total borrowing. Your existing balance moves on its old rate, and the extra you need is a second product at today's rates — so a port to a more expensive home is really a part-port, part-new-borrowing application, all with your current lender.
Do I have to reapply to port my mortgage?
Yes — a port is a full application with your current lender: new valuation on the property you're buying, fresh affordability and criteria checks on you. Only the deal itself is guaranteed by portability, and only once the lender approves the new lending.
Can my lender refuse to port my mortgage?
Yes. Portability makes the product transferable; it doesn't oblige the lender to approve the new loan. Changed income, new credit issues or tightened criteria can all sink it. A refusal from your own lender doesn't end the move — it changes the comparison to "new mortgage elsewhere, minus the ERC".
Do I pay an early repayment charge if I port?
Not on the amount you port. You can still meet an ERC if you port only part of the balance (it's typically charged on the part repaid), or if your sale and purchase don't complete close enough together and the loan has to be redeemed in between. Some lenders refund an ERC when you buy again within a set window — check the porting section of your offer.
Does porting work if I'm moving out of Cardiff?
Yes — the deal moves anywhere in the UK the lender will lend, subject to the same re-checks; a move to Newport or anywhere else in South Wales ports exactly as a move across Cardiff does. The property still has to pass the lender's valuation and criteria wherever it is.
Where to go next
If your fix has ended — or the numbers put a full switch back on the table — the remortgaging in Cardiff guide covers the other side of this decision, including ERC arithmetic and realistic timelines. For the move itself, the salary needed for a Cardiff house guide sets the price context, and the affordability check shows lender by lender what your income supports — ported, topped up, or fresh.