Let to buy is one of the most underused strategies in UK property. If your current home would make a good rental, you can keep it as an investment rather than selling, using the rental income to support the old mortgage while taking a new mortgage on your next home.\n\nHow It Works — You switch your existing residential mortgage to a consent-to-let or buy-to-let product. You then apply for a new residential mortgage on the property you want to buy. The rental income from your old home supports the BTL mortgage, and your salary supports the new residential mortgage. You end up owning two properties.\n\nConsent to Let vs Buy-to-Let Remortgage — Consent to let is a temporary arrangement where your existing lender allows you to let the property on your current residential mortgage. It is usually granted for 12 months and may carry a small rate increase. A BTL remortgage is a permanent switch to a dedicated buy-to-let product with a different lender. The BTL remortgage is the cleaner long-term solution but involves a full application, valuation, and legal process.\n\nAffordability — The key challenge is proving you can afford both mortgages. For the new residential mortgage, lenders consider your income minus any committed expenditure. The old BTL mortgage is not usually counted as a full commitment because the rental income offsets it, but different lenders treat this differently. Some count 100% of rental income as offsetting the BTL payment. Others use a more conservative calculation. A broker who understands let-to-buy structuring is essential.\n\nStamp Duty Implications — Because you will own two properties at the point of buying the new one, the additional property surcharge of 5% applies to the new purchase. On a 300,000 property, this adds 15,000. However, if you designate the new property as your main residence and sell the old one within 36 months, you can claim a refund of the surcharge. If you intend to keep both properties permanently, the surcharge is a sunk cost.\n\nDeposit Requirements — You need a deposit for the new residential purchase (5-15% depending on the mortgage) and sufficient equity in the old property for the BTL remortgage (usually 25% minimum). If your old home has appreciated significantly, the equity position should be comfortable. If you bought recently with a small deposit, you may not have enough equity for a 75% LTV BTL product.\n\nTax Considerations — Rental income is taxable. Section 24 restricts mortgage interest relief for personal landlords to a 20% tax credit. If you are a higher-rate taxpayer, consider whether a limited company structure makes sense for future purchases. Capital gains tax applies when you eventually sell the rental, though private residence relief may apply for the period you lived there.\n\nWhen It Makes Sense — Your current home is in a strong rental area with yields above 5%. You have significant equity. Your income supports both mortgages. You believe the property will appreciate long-term. You want to build a property portfolio starting with a home you already know well.\n\nWhen It Does Not — The rental yield is low (common in expensive areas). You need the sale proceeds as a deposit for the next home. Managing a rental property while moving is too stressful. The stamp duty surcharge makes the numbers unworkable.