What let to buy is — and who it’s actually for

Let to buy is buy-to-let in reverse gear: instead of buying a property to rent out, you rent out the property you already own and buy a new one to live in. (Worth one sentence of disambiguation: it’s also different from remortgaging to buy a second home, where your current home stays your main residence and you’re adding a holiday home or investment — in let to buy, the roles swap: old home becomes the rental, new home becomes your life.)

The recurring cast of let-to-buy users:

• The chain-breaker — found the perfect next home, can’t sell fast enough (or won’t sell into a soft market). Let to buy removes the sale from the critical path entirely.
• Couples moving in together — two owners, one shared future: live in one (or a new third), let the other. One of the most common triggers.
• The relocator — moving for work, maybe temporarily, wanting the option to come back to the old house and area.
• The deliberate investor — always wanted a rental; the home you already own, with its accumulated equity and known quirks, is the lowest-friction way in. (Once you’re running it as an investment, our buy-to-let guide covers the ongoing landlord economics.)

How the two mortgages work

A let-to-buy transaction is two applications choreographed to complete together — usually on the same day:

• Side one: the let-to-buy remortgage. Your current residential mortgage is replaced with a buy-to-let-basis loan. Two jobs happen at once: the switch makes letting the property legitimate, and — where equity allows — you borrow more than you currently owe and release the difference as cash for your next deposit. The loan is sized by two caps: typically 75% of the property’s value, and whatever the rental coverage test supports (below). A letting agent’s rental valuation is standard evidence.
• Side two: the new residential mortgage. A normal home-buyer application for the place you’re moving to — with one crucial kindness: because the old property’s mortgage is covered by its rent, most lenders exclude it from your affordability assessment. Your income buys the new home; the tenants buy the old one. That exclusion is the engine of the whole structure — without it, almost nobody could afford two mortgages on one salary.
• The synchronisation. Lenders on the residential side generally want evidence of the onward structure (and vice versa), and completion is coordinated so you never illegally let a home on a residential mortgage or own two residences unintentionally. This choreography — two lenders, two criteria sets, one date — is why let to buy is overwhelmingly broker-arranged.

The worked example

Criteria: what both lenders check

Not every lender offers let to buy, and among those that do, some insist on providing both sides while others happily take one half — pairing the two lenders (and their timing quirks) is where placement skill genuinely changes outcomes.

The costs: read this section twice

• The stamp duty surcharge — the big one. On completion day you own two properties, so the new home attracts the 5% additional-property surcharge on top of standard SDLT. On a £350,000 onward purchase that’s roughly £25,000 total (£7,500 standard + £17,500 surcharge) versus £7,500 for a plain mover — and it’s cash, not mortgageable. The escape hatch: sell the old home within 36 months and the surcharge is refunded — which makes let to buy a surprisingly reasonable “not sure yet” structure, but an expensive forever-decision made casually. Wales and Scotland run their own (higher-starting) additional-property rates. Full bands and refund mechanics in our additional-property stamp duty guide.
• Higher rates on the let side. Buy-to-let-basis pricing runs above residential, with product fees to match — the price of the tenant-funded structure.
• The tax tail. Rental income is taxable (with mortgage interest relief restricted to a 20% credit — the Section 24 effect that stings higher-rate taxpayers), and if you eventually sell the old home, capital gains tax applies to the let period (private residence relief covers your years living there, plus the final nine months). Neither kills the structure; both belong in the spreadsheet before you commit.

Let to buy vs consent to let vs just selling

• Consent to let — your current lender’s permission to rent the home out on your existing residential mortgage, usually temporary (6–24 months) and sometimes with a rate loading. The right tool for genuinely short-term situations — a trial relocation, a slow sale — with no remortgage costs. Its limits: no equity release, time-boxed, and discretionary.
• Let to buy — the permanent, equity-releasing version above. Right when the plan is to keep the property for the long haul and you need its equity for the next purchase.
• Selling — the honest default. No surcharge, no landlord life, all equity liberated, cleanest affordability. Let to buy should beat selling on the numbers and the intention — a wanted investment, a market you believe in, a possible return to the property — not merely postpone it. If the goal is simply releasing money from a home you’re staying in, that’s a different tool: our equity release remortgage guide.

The landlord reality check

The moment tenants move in, you’re running a small business with statutory duties: gas and electrical safety certificates, deposit protection, right-to-rent checks, EPC standards, compliance with the Renters’ Rights regime, repairs on someone else’s timetable — plus the financial realities of void periods (budget 4–6 weeks a year), maintenance (~10% of rent), and agent fees (8–15% if you’d rather outsource the 2am boiler calls). None of this is a reason not to do it; all of it is the difference between a structure that works on paper and one that works on a wet Tuesday in February. Accidental landlords who thrive are the ones who priced the job honestly first.

Let to buy: FAQs

Last updated: July 2026. Criteria and tax rules verified at the time of writing and subject to change.