Moving home: port, new deal, or let-to-buy?

When you move house, the mortgage question has three broad answers: take your current deal with you (porting), end it and start fresh (a new mortgage, with or without an exit penalty), or keep your current home as a rental and mortgage the new one (let-to-buy). Most movers only hear about the first two, and plenty pick between them on instinct rather than numbers. This guide is the orientation; the full process detail lives on our moving home hub.

Route 1: port your current mortgage

Porting takes your existing product, the rate and terms, to the new property. The big draw is avoiding the early repayment charge (ERC, the penalty for ending a fixed deal early, typically 1-5% of the balance), and keeping a rate you like. The catches: it's a full re-application (affordability, credit check, the new property passing criteria), and any extra borrowing sits on a separate product at today's rates. Porting tends to win when your existing rate beats today's market and the ERC is chunky. Our porting guide covers the mechanics, including what happens if your sale and purchase don't complete on the same day.

Route 2: take a new mortgage

End the current deal, repay it from the sale, and finance the new home with whichever lender and product fit best now. This wins automatically if your deal ends around moving time (no ERC to avoid), and often wins even mid-fix when today's rates are better than your existing one, when your current lender won't lend what the new home needs, or when the new property doesn't fit their criteria. The decision is arithmetic, not philosophy: ERC plus any fees versus what the better rate or bigger loan saves and enables over the next deal period. We run that comparison both ways on real numbers, it takes minutes and regularly changes minds in both directions.

Route 3: let-to-buy, keep the old home and rent it out

Let-to-buy means converting your current home onto a buy-to-let mortgage (assessed mainly on the rent it can earn, via an interest coverage ratio (ICR), the rent-to-mortgage-interest test lenders apply), usually releasing some equity in the process, then using that equity as the deposit on a new residential mortgage for the home you're moving to. Both completions are typically arranged simultaneously.

It can be a strong structure: you keep an asset you know, gain rental income, and move without waiting to sell. But go in with eyes open:

• Stamp duty surcharge. You'll own two properties on completion day, so the additional-property surcharge applies to the new purchase, and because you're keeping the old home, there's no later refund. This is often the decisive cost.
• You become a landlord, with everything our becoming-a-landlord guide describes: compliance, voids, repairs, tax on the rent, and an Energy Performance Certificate (EPC) meeting the rental minimum.
• Both mortgages must stack up. The buy-to-let needs the rent to pass the lender's ICR; the new residential needs your income to carry it, with most lenders satisfied the old home is self-financing.
• A quick word on consent-to-let: if the move is short-term or exploratory, your current lender may grant temporary consent to let on your existing residential mortgage instead, simpler, but time-limited and product-restricted. Full let-to-buy is the durable structure.

How to choose

Honest first-pass questions: Is your current rate better or worse than today's market? How big is the ERC, and does your timing avoid it anyway? Do you need more borrowing than your current lender will stretch to? Would you actually want to be a landlord, and does the old home make sense as a rental once the surcharge and tax are counted? The answers usually eliminate one route immediately and set up a two-way numbers comparison we can run quickly.

Timing-wise, start the mortgage conversation at least three months before you expect to offer, an Agreement in Principle (AIP, a lender's soft-checked indication of what they'll lend) in place before viewings makes you a stronger buyer and surfaces any problems while they're still fixable. Budget properly too: our moving costs guide itemises what the move itself will cost beyond the mortgage.

If you're weighing these routes for a real move, book a quick 15-minute call, we'll tell you which options are realistic for your numbers, and the moving home hub has the deeper process detail when you want it.