Overview
Downsizing should reduce housing costs, but a portable mortgage does not mean every pound of the existing loan can move unchanged to a cheaper property.
The amount you want to borrow, the new property's value and the lender's current criteria all matter. If you repay part of the existing mortgage, an early repayment charge may also need to be included.
Quick Answer
You may be able to port a mortgage deal to a cheaper home, subject to approval. If the new loan is smaller, the part repaid can attract an early repayment charge under the product terms.
Calculate the new loan-to-value and obtain a written cost breakdown. A cheaper purchase price does not automatically mean a lower LTV or a charge-free move.
Start With Sale Proceeds, Not Just the New Price
Work out the equity released from the sale after repaying the existing loan and allowing for selling costs. Then decide how much of that money will go into the new property.
Do not count money twice: sale equity used for fees, repairs or another purpose is not also available as the new deposit.
Our mortgage-porting guide explains the basic process. Porting concerns the product arrangement; the new property still needs approval.
A Downsizing Example
Assume the current home sells for £300,000 and the mortgage balance is £180,000. Before costs, the equity is £120,000.
If the new property costs £240,000 and all £120,000 is used towards it, the new mortgage would be £120,000. You would be reducing the loan by £60,000, and the new LTV would be 50%.
If you instead keep £40,000 aside, the deposit becomes £80,000 and the required loan £160,000. The new LTV is about 66.7%.
These figures exclude costs and assume the lender accepts the values and borrowing. They show why the purchase price alone does not determine the mortgage.
What Happens to the Part You Do Not Port?
Ask the lender to calculate any early repayment charge on the reduction. Do not assume its ordinary annual overpayment allowance applies to a partial port in exactly the way you expect.
For illustration only, a 3% charge on a chargeable £60,000 reduction would be £1,800. The actual chargeable amount and percentage come from your mortgage terms and the lender's calculation.
Nationwide's published porting material identifies circumstances where early repayment charges can apply, including changes to the amount and timing of the move. Other lenders have their own rules.
See overpayment limits and charges for the wider distinction.
Could the New LTV Be Higher?
Yes. Suppose the existing £180,000 loan is secured on a £300,000 home: the LTV is 60%.
Keeping a £180,000 loan against a £240,000 purchase would produce a 75% LTV, despite buying a cheaper home. Whether that structure is possible depends on affordability, deposit arrangements and lender criteria.
Do not assume a rate portable at one LTV is automatically available in every new scenario. Ask the adviser to check the proposed balance and valuation explicitly.
Our LTV guide explains the calculation.
Affordability Still Matters
Downsizing may happen because income is falling, retirement is approaching or the household has changed. Those changes can be relevant to a new application.
An existing payment history does not replace the lender's assessment of the new mortgage. The property type and remaining term can matter too.
If the lender refuses the port, find out which part failed. Our porting-declined guide explains the next steps without assuming another lender will solve every issue.
Watch a Gap Between Sale and Purchase
Selling before buying may mean the old mortgage is repaid before the new one starts. A lender may have specific arrangements for an early repayment charge and a later refund if a qualifying purchase completes within its window.
Do not assume such a window exists or that an expected purchase date is enough. Obtain the conditions, deadline and refund process in writing.
Include the possibility of a delayed purchase in your budget. A refund that depends on a future event should not be treated as cash already available.
Compare the Whole Move
Ask for a comparison of porting the reduced balance and taking an entirely new deal, including any charge for leaving the old product.
Add legal costs, valuation fees where applicable and the interest cost over a consistent period. A low existing rate can be valuable, but it does not remove the need to compare the actual amounts.
Frequently Asked Questions
Explore mortgage guides. Your home may be repossessed if you do not keep up repayments on your mortgage. Examples are illustrative, not personalised advice.
