Are buy-to-let mortgages more expensive than residential?

Yes, typically. Rates run higher and arrangement fees can be chunkier, because the lender carries tenant risk, void risk and a landlord's business risk. Price it into the deal from day one.

Can I get a buy-to-let mortgage without owning my own home?

Sometimes. A minority of lenders accept first-time buyers, usually with stricter criteria and stronger deposits. A broker will tell you quickly whether your situation fits.

How much can I borrow on a buy-to-let mortgage?

It is driven by the rent, not your salary. As a rough shape: annual rent, divided by the lender's coverage ratio (125% to 145%), divided by their stress rate, gives the ceiling. Your own income then acts as the backstop rather than the driver.

Buy-to-Let Mortgages Explained: How They Actually Work

If you have only ever had a residential mortgage, the buy-to-let version feels like the same product wearing different rules. Same monthly payment, same solicitor, completely different logic underneath. After a decade of walking investors through it, here is the whole thing in plain English.

What is a buy-to-let mortgage?

It is a mortgage on a property you intend to let to tenants. That single difference changes everything about how the lender thinks. On your own home, they are lending against your salary and your reliability. On a rental, they are lending against the property's ability to earn, with your finances as the backstop. It is closer to a small business loan than a home loan, and the pricing, the deposit and the paperwork all follow from that.

Two practical differences surprise people most. First, the majority of buy-to-let mortgages are taken interest-only: you pay just the interest each month, the loan itself stays the same, and the plan for repaying it is the eventual sale, a refinance, or overpayments along the way. That keeps monthly costs down and cashflow healthy, which is why landlords favour it. Second, letting a property on an ordinary residential mortgage without the lender's permission is a breach of your terms, and lenders treat it seriously. Rental property needs a rental mortgage or written consent, no exceptions worth having.

How do buy-to-let mortgages work when it comes to borrowing?

Residential lending asks "what do you earn?" Buy-to-let lending asks "what will it rent for?"

Lenders run what is called an interest coverage ratio, or ICR. In plain terms: the expected monthly rent must comfortably exceed the mortgage interest, typically by 125% to 145%, and they test it at a stressed interest rate higher than the one you will actually pay, to prove the deal survives bad weather.

Here is the mechanics on an illustrative example. Say a property rents for £900 a month, £10,800 a year. At a 145% coverage requirement, the lender allows up to about £7,400 a year in interest. Test that at a stressed rate of 5.5% and it supports roughly £135,000 of borrowing. Every lender sets its own ratios and stress rates, so treat that as the shape of the calculation rather than a promise, but the lesson is universal: the rent decides the loan. It is exactly why we choose properties rent-first, and why a pretty house with weak rent is a weak deal.

What criteria do lenders check?

Beyond the rent, most lenders look at:

Deposit. Typically 25%, floor around 20%, best pricing at 40%. The full breakdown, including the costs beyond the deposit, is in our deposit guide.
Your income. Many want a minimum personal income, often around £25,000 with some lenders, as the backstop if the property sits empty.
Your credit history. Clean is easiest; blips narrow the pool rather than close it.
Age. Lenders set minimum ages, commonly 21 or 25, and maximum ages at the end of the term, often 75 to 85. Property investing suits patient people, and the lenders agree.
Owning your own home. Preferred by many lenders, insisted on by some. First-time buyers can get buy-to-let mortgages, but from a smaller pool with stricter terms.
The property itself. Solid, standard-construction houses sail through. Some lenders are wary of high-rise flats, non-standard construction and anything unusual. Another quiet argument for the boring house on the ordinary street.

Personal name or limited company?

Both routes exist and the mortgage works similarly in either. The differences are tax-driven: interest treatment, corporation tax versus income tax, and how you take the money out. We covered the honest trade-offs in our rental income tax guide, and it is a decision for you and your accountant before you apply, because switching later means remortgaging.

How to get a buy-to-let mortgage: the process

Broker first. Buy-to-let criteria vary wildly between lenders, and a good broker maps your situation to the right ones. Going straight to your own bank is rarely the best outcome.
Decision in principle. Free, fast, and it sets your real budget before you fall for anything.
Property chosen on the numbers. Rent coverage first. Run it through our investment calculator before anyone gets excited.
Application and valuation. The lender values the property and, crucially, checks the rental figure with their own surveyor.
Offer, legals, completion. Then the actual work begins: refurbishment, tenants, management.

If coordinating brokers, solicitors and surveyors sounds like a second job, that coordination is literally what our service does, end to end, with you approving the decisions.

What I would tell you if you were family

Do not shop for a mortgage. Shop for a deal that survives stress-testing at today's rates with room to spare, then let a broker find the mortgage that fits it. Landlords get into trouble in exactly one way: numbers that only worked in the sunshine. The lender's stress test is not bureaucracy, it is a free second opinion on whether your deal is honest. If a purchase only passes when you nudge the rent up or the rate down, thank the spreadsheet for its candour and walk away.