A buy-to-let (BTL) mortgage is designed for properties you plan to rent out rather than live in. The lending criteria, interest rates, and tax treatment are all different from a standard residential mortgage. If you're thinking of becoming a landlord, understanding these differences is essential before you commit your capital.
Deposit requirements
Most buy-to-let mortgages require a minimum 25% deposit, compared to 5-10% for residential. Some specialist lenders accept 20%, but you'll pay higher rates. The most competitive deals typically require 40% or more.
A 25% deposit on a £200,000 property is £50,000 — a substantial sum. Add stamp duty (with the 5% surcharge on additional properties), solicitor fees, and any renovation costs, and you're looking at needing £65,000+ in cash to get started.
How lenders assess affordability
BTL mortgage affordability is based primarily on rental income rather than your personal earnings. Most lenders require the expected rent to cover 125-145% of the monthly mortgage payment at a stress-tested interest rate (typically 5-5.5%, regardless of the actual rate you're paying).
For example, if the mortgage payment at the stress rate would be £800/month, the rental income needs to be at least £1,000-£1,160/month. If the sums don't stack up, the lender will either reduce the loan amount or decline the application.
Some lenders also consider your personal income as a top-up — useful if the rental coverage falls slightly short. But the core assessment remains rental-income based.
Interest rates
BTL mortgage rates are typically 0.5-1.5% higher than equivalent residential rates. This reflects the lender's view that rental properties carry more risk — void periods, problem tenants, and regulatory changes can all affect a landlord's ability to pay.
Most BTL mortgages are interest-only, meaning you only pay the interest each month and the capital balance doesn't reduce. This keeps monthly costs lower and maximises rental yield, but you need a plan to repay the capital eventually — usually through selling the property. Repayment BTL mortgages exist but are less common.
Tax changes that affect landlords
Several tax changes have made buy-to-let less attractive than it used to be:
- Mortgage interest tax relief — landlords can no longer deduct mortgage interest from rental income before calculating tax. Instead, you get a 20% tax credit on the interest paid. Higher-rate taxpayers are significantly worse off under this system.
- Stamp duty surcharge — 5% on top of standard SDLT rates for additional properties
- Capital gains tax — gains on selling a BTL property are taxed at 18% (basic rate) or 24% (higher rate), with the annual exempt amount now just £3,000
These changes have squeezed profit margins, particularly for higher-rate taxpayers. Many landlords have responded by incorporating — buying through a limited company, which still gets full mortgage interest relief. But incorporating adds its own complexity and costs.
Landlord responsibilities
Being a landlord comes with legal obligations. You must:
- Provide an Energy Performance Certificate (EPC) rated E or above
- Install smoke and carbon monoxide alarms
- Conduct annual gas safety checks
- Protect tenants' deposits in a government-approved scheme
- Ensure the property meets the Homes (Fitness for Human Habitation) Act standards
- Comply with right-to-rent immigration checks
Failing to meet these requirements can result in fines and make it harder to evict tenants if problems arise. The regulatory burden has increased significantly in recent years, and further licensing requirements are being introduced by many local councils.
Is buy-to-let still worth it?
The honest answer: it depends on your tax position, the local rental market, and how hands-on you want to be. Net rental yields (after mortgage costs, tax, maintenance, void periods, and management fees) are often lower than people expect — sometimes 3-4% in high-value areas. Factor in the capital tied up in the deposit, and the return needs to be compared against alternatives like pension contributions or stock market investments.
Buy-to-let can still work, particularly in areas with strong rental demand and reasonable property prices. But the days of easy, tax-efficient landlord profits are behind us.