If you are moving home and have a mortgage deal you want to keep — particularly if it has a competitive rate or you would face early repayment charges for leaving — porting your mortgage lets you transfer the existing deal to your new property. Here is how it works and what to consider.
How Porting Works
When you port a mortgage, you essentially take your current deal with you to a new property. The key features transfer:
- Interest rate — stays the same
- Remaining deal period — if you have two years left on a five-year fix, you keep those two years
- Terms and conditions — overpayment allowances, ERCs, and other terms carry over
However, it is not a simple administrative transfer. The lender treats it as a new mortgage application on the new property, meaning:
- Full affordability assessment based on current criteria
- New property valuation
- Full credit check
- Possible changes if your circumstances have altered
When Porting Makes Sense
| Scenario | Port? | Reason |
|---|---|---|
| Your rate is well below current market rates | Yes | Keeping a cheaper rate saves money |
| You would face a large ERC | Yes | Avoiding the ERC outweighs other costs |
| Your rate is above current market rates | No | A new deal would be cheaper |
| Your ERC is small or zero | Maybe | Compare the cost of ERCs vs new deal savings |
| You need significantly more borrowing | Depends | Partial port plus new borrowing may work |
The Porting Process
- Notify your lender — tell them you intend to move and want to port your mortgage
- Affordability check — the lender reassesses your income, expenses, and credit
- Property valuation — the lender values your new property
- Approval — if everything passes, the lender confirms the port
- Completion — your solicitor handles redemption on the old property and drawdown on the new
The timing must align — ideally, you complete the sale of your old property and the purchase of your new one on the same day. Most lenders allow a short gap (often 30 days) between selling and buying, but check your lender’s policy.
Borrowing More When You Port
If your new property costs more than the ported mortgage balance, you will need additional funds. Options include:
Additional Borrowing from the Same Lender
Most lenders offer a top-up alongside the ported amount. This additional borrowing will be on a separate deal at current rates, meaning you end up with two products:
- Product 1: Your ported mortgage at the original rate and remaining term
- Product 2: New borrowing at the current rate on a new deal
Example
| Product | Balance | Rate | Monthly Payment |
|---|---|---|---|
| Ported mortgage | £150,000 | 3.50% (original deal) | £751 |
| Additional borrowing | £100,000 | 4.75% (current rate) | £573 |
| Combined | £250,000 | Blended | £1,324 |
Downsizing
If your new property is cheaper, you will be repaying part of your mortgage. Check whether the amount you repay exceeds your annual overpayment allowance, as this could trigger an ERC on the excess.
Potential Problems with Porting
Affordability Decline
If your income has fallen, you have taken on additional debt, or lending criteria have tightened since you took out the mortgage, the lender may decline your port. This is one of the most common issues borrowers face.
Property Type Changes
Moving from a standard property to a non-standard construction, a flat above commercial premises, or a property with a very short lease may cause the lender to decline. Each lender has its own acceptable property criteria.
Timing Gaps
If there is a gap between selling your current home and buying your new one, the ported mortgage may lapse. Check your lender’s gap policy — some allow 30 days, others up to a few months.
Part-Porting
Not all lenders allow partial porting (taking only part of your balance to the new property). If you are downsizing significantly, check that your lender permits this.
Porting vs Remortgaging — What Is Better?
The answer depends on the numbers:
Calculate the cost of porting:
- Monthly payments at your current rate for the remaining deal period
Calculate the cost of a new mortgage:
- Monthly payments at the best available new rate
- Plus early repayment charge on your existing mortgage
If the ERC wipes out the savings from a lower new rate, porting is likely better. If the new rate saves you more than the ERC costs, remortgaging wins.
Use our mortgage calculator and repayment calculator to compare both scenarios before deciding.
Checklist Before Porting
- Confirm your mortgage is portable (check your terms or call your lender)
- Calculate any ERC you would face if you did not port
- Compare your current rate to the best available new deals
- Check whether your lender allows additional borrowing alongside the port
- Think about timing — aim to complete sale and purchase on the same day
- Speak to a mortgage broker who can run the full comparison for your situation