Buying a rental property can be an exciting step — whether you’re looking to create a long-term investment, build a property portfolio, or generate an additional income stream.
But buy-to-let (BTL) mortgages work very differently from residential mortgages, and understanding the landscape early makes everything easier.
Our goal is to keep things clear, honest, and human so you can invest with confidence, not confusion.
What is a buy-to-let property?
A buy-to-let (BTL) property is one you purchase with the intention of renting it out. Unlike a residential mortgage, which is based largely on your personal income, BTL mortgages focus heavily on the rental income the property can generate.
Whether it’s a single flat, a family home, or part of a growing portfolio, the key idea is the same: the property should be capable of covering its own mortgage through rental income.
Why do people invest in buy-to-let?
People buy rental properties for different reasons. Some invest for long-term capital growth, hoping the value of the property will rise over time. Others want a steady rental income to supplement their salary or support future retirement plans.
Some enjoy the control and predictability of owning a physical asset rather than relying purely on stocks or pensions. Whatever the motivation, a BTL can be a valuable part of a wider financial strategy when approached with the right guidance.
What eligibility criteria do lenders look for?
Eligibility for a BTL mortgage is different from a residential one. Many lenders require you to own your own home already, have a minimum income (often around £25,000), and demonstrate good credit history. Some lenders also place restrictions based on age, property type, or portfolio size.
Even if you don’t meet every traditional criterion, there are still lenders who take a more flexible approach — which is where advice becomes invaluable.
How does buy-to-let affordability work?
Affordability for BTL mortgages is driven mainly by rental income. Lenders calculate something called an Interest Coverage Ratio (ICR) to ensure the property can comfortably cover the mortgage payments. They also apply stress tests, which check how the mortgage would perform if interest rates rose.
Your personal income can still play a role, especially for higher-rate taxpayers or specialist cases, but the property’s rental potential sits at the heart of the assessment.
How much deposit do I need?
BTL mortgages typically require a larger deposit than residential ones. Most lenders ask for at least 25%, and some specialist products may require more. A larger deposit can open up better rates and improve the rental calculations, giving you more choice across the market.
If you’re building a portfolio, planning deposit strategy becomes even more important — and we’ll help you map that out.
What fees should I expect?
Buy-to-let purchases come with several costs: mortgage arrangement fees (which are often higher on BTL products), valuation fees, legal fees, stamp duty, and letting agent costs if you’re using one.
Some lenders charge percentage-based product fees, which can be worthwhile on large loans but less attractive on smaller ones. We’ll break down the full picture so you understand exactly what to expect and how each fee affects the overall value of the deal.
Should I buy in my personal name or through a limited company?
This is one of the most common questions for new and experienced landlords alike. Buying in your personal name is typically simpler and may offer cheaper mortgage rates. However, purchasing through a limited company can be more tax-efficient for many investors, particularly higher-rate taxpayers, because of the way profits and interest are treated.
The right route depends on your tax position, your long-term plans, and whether you intend to build a portfolio. It is important to speak to an accountant to ensure your structure supports both your investment goals and your tax efficiency.
Repayment vs. interest-only mortgages
Most BTL investors choose interest-only mortgages because they keep monthly payments lower and improve rental affordability. The capital is repaid later — either when the property is sold or through a planned repayment strategy.
Repayment mortgages, on the other hand, gradually reduce your loan and can build equity more quickly, but they come with higher monthly payments. There’s no “right” option; it depends on your strategy, time horizon, and risk appetite.
AST vs. Airbnb: what’s the difference?
Letting your property on a standard Assured Shorthold Tenancy (AST) is the most common route. It involves a traditional long-term tenancy, and most lenders’ criteria and rental calculations are built around this model.
Short-term lets, such as Airbnb, follow a different pattern. They can produce higher income but come with more volatility, higher running costs, and far fewer mortgage options.
Many lenders do not allow Airbnb at all, while others offer specialist products with stricter criteria. If you’re considering short-term lets, it’s crucial to choose the right mortgage from the start.
What should professional landlords consider?
If you already own multiple properties, lenders class you as a portfolio landlord.
This means more detailed underwriting: rental assessments across the whole portfolio, business-plan reviews, and sometimes proof of experience. While it sounds complex, it’s very manageable with the right preparation.
What is an HMO and how does it work?
A House in Multiple Occupation (HMO) is a property rented to three or more unrelated tenants who share facilities like kitchens or bathrooms.
HMOs can generate higher rental yields but also come with stricter regulations, licensing requirements, and specialist mortgage products. Not all lenders offer HMO mortgages, and criteria vary widely — including minimum experience levels for landlords.
Why should I use a broker for buy-to-let?
Buy-to-let mortgages are more specialised than standard residential ones, with different affordability rules, tax considerations, lending criteria, and product types. A broker helps you navigate all of that without the stress or confusion of trying to piece it together alone.
When you work with us, we compare lenders across the whole market — including specialist providers you won’t find on comparison sites — to make sure the mortgage fits your investment strategy, not just the property.
We help you understand rental calculations, portfolio rules, limited company lending, and the long-term financial implications of each decision.
Just as importantly, we coordinate the process from start to finish: checking eligibility, assessing rental figures, managing applications, and ensuring the mortgage runs smoothly alongside the purchase.
Whether you’re buying your first rental or expanding a portfolio, you get clear advice, honest guidance, and a partner who helps you make decisions with confidence.
