Buy to Let Mortgages: How Do They Work?

Whether you are an experienced landlord or considering your first rental property, understanding buy to let mortgages is essential before you commit to a purchase.

A buy to let mortgage is a specialist product designed specifically for properties you intend to rent out, and using the wrong type of mortgage can have serious financial and legal consequences. This guide walks you through why landlords need a dedicated buy to let mortgage, the different types available, and how to put yourself in the best position when you apply.

Why Landlords Need a Buy to Let Mortgage

When you buy a home to live in yourself, you take out a residential mortgage. When you buy a property to rent to tenants, you need a buy to let mortgage. These are two fundamentally different products and lenders treat them very differently, for good reason.

With a standard residential mortgage, affordability is based primarily on your personal income. A buy to let mortgage takes a different approach: lenders focus heavily on the rental income the property is expected to generate. Most will require that the projected monthly rent covers at least 125% to 145% of the monthly mortgage payment, depending on the lender and whether you are a basic or higher rate taxpayer.

Using a residential mortgage on a property you intend to rent out without telling your lender – known as ‘consent to let’ fraud – can put you in breach of your mortgage terms. This could result in the lender demanding repayment in full. Beyond the legal risk, residential mortgages simply are not structured to account for the realities of being a landlord, such as void periods, maintenance costs, and rental market fluctuations.

It is also worth noting that buy to let mortgages typically require a larger deposit than residential products. Usually a minimum of 25% of the property value, though some lenders will consider 20%. Buy to let mortgage rates also tend to be slightly higher than residential rates, reflecting the additional risk lenders take on. Using a buy to let mortgage broker can help you model different scenarios before you commit, giving you a clearer picture of what monthly repayments and potential yields might look like at various deposit and loan sizes.

Keen to learn more? Get in touch

Different Types of Buy to Let Mortgages

The buy to let mortgage market has broadened considerably in recent years, and there is now a range of products to suit different landlord circumstances. Understanding the main types will help you identify which one might be the right fit.

Fixed Rate Buy to Let Mortgages

A fixed rate deal locks in your interest rate for a set period, typically two, three, or five years. Your monthly repayment stays the same throughout the fixed term, making it easier to budget and forecast rental yields. Fixed rates are particularly popular when buy to let mortgage rates are low and landlords want to protect themselves from future increases. At the end of the fixed period, you would typically remortgage onto a new deal.

Tracker and Variable Rate Mortgages

Tracker mortgages follow the Bank of England base rate, moving up or down with it. Variable rate mortgages move at the lender’s discretion. Both can offer lower initial rates than fixed deals, but they come with less certainty, which can make cashflow planning more challenging for landlords.

Interest-Only Buy to Let Mortgages

A majority of buy to let landlords opt for interest-only mortgages. With this structure, your monthly payment covers only the interest on the loan, not the capital itself. This keeps monthly costs lower and can improve rental yield calculations significantly. The full loan amount remains outstanding and is typically repaid when the property is sold. Many landlords use property appreciation over time as their exit strategy, though this involves risk and requires careful planning.

Personal vs. Limited Company Buy to Let Mortgages

An increasingly common question among landlords is whether to hold a buy to let property in their personal name or through a limited company (often called an SPV — Special Purpose Vehicle). Since changes to mortgage interest tax relief for individual landlords, limited company structures can be more attractive for higher rate taxpayers. However, limited company buy to let mortgages can come with higher rates and fees, and the overall decision involves tax, legal, and financial considerations. It is strongly advisable to speak with a specialist buy to let mortgage advisor before deciding which route is right for you.

HMO Mortgages

If you are considering a House in Multiple Occupation – a property rented by three or more unrelated individuals – you will need a specialist HMO mortgage. These are more complex products with stricter criteria, but they can offer significantly higher rental yields due to the room-by-room rental model.

How to Prepare for a Buy to Let Mortgage Application

A well-prepared application will give you access to the best buy to let mortgage rates available for your circumstances. Here is what lenders will typically look at, and how you can get ready.

• Deposit: Most lenders require a minimum of 25% deposit for a buy to let mortgage. The larger your deposit, the better the rates you are likely to access, as a lower loan-to-value ratio represents less risk to the lender.
• Rental income: Lenders will want a rental assessment, often carried out by a local letting agent, to confirm the property can command sufficient rent to cover the mortgage stress test. Understanding the local rental market in your target area is important before you commit.
• Personal income: While rental income is the primary focus, most lenders also require landlords to earn a minimum personal income, typically around £25,000 per year, from employment or other sources.
• Credit history: A clean credit record will help you access more lenders and better rates. Check your credit report in advance and address any errors or outstanding issues before applying.
• Existing portfolio: If you already own rental properties, lenders will want to understand your existing portfolio. Some lenders have limits on the number of buy to let properties they will lend against, so a specialist advisor becomes particularly important for portfolio landlords.

Contacting a buy to let mortgage advisor before you apply is a sensible first step. It can help you understand what loan size may be available based on expected rental income, and give you a sense of how different buy to let mortgage rates affect your monthly outgoings and overall yield.

Get In Touch

Get the Right Advice Before You Commit

The buy to let mortgage market is wide, and the right product depends heavily on your personal circumstances including your income, tax position, portfolio size, and long-term strategy. Working with a qualified buy to let mortgage advisor ensures you are not only comparing rates across the full market, but also structuring your investment in the most tax-efficient and financially sound way.

If you are based in the South West and looking for a buy to let mortgage advisor, Exe Mortgages specialises in exactly this area. As an independent mortgage advisor, we search the whole of market to find the right deal for your situation whether you are a first-time landlord buying your initial property, or an experienced investor looking to expand your portfolio.

Get in touch today to speak with a specialist buy to let mortgage advisor and take the first step towards your next property investment.