How to choose a buy-to-let lender: a guide for landlords

Search for the best buy-to-let lender and you will find ranked lists that are out of date within weeks, because rates move constantly. The more useful question is not which lender tops a table today, but which lender will actually lend to you, on your property, at the loan you need. This guide explains how to choose a buy-to-let lender: the criteria that decide fit, how to match a lender to your situation, and why most landlords work through a broker.

Rate is not the place to start

The cheapest headline rate means very little if the lender declines your case, or will not lend on your property type, or caps its loan below what you need. And a low rate with a large percentage fee can easily cost more over a fix than a higher rate with no fee. The lender that will lend to you, at the loan-to-value and loan size you need, matters more than being a fraction of a percent cheaper. Start with fit, then optimise cost within the lenders that fit.

The types of buy-to-let lender

Rather than a list of names that changes constantly, it helps to think in three broad types.

Mainstream banks and larger building societies offer the sharpest rates on standard, good-credit, single-let cases at lower loan-to-values. Their criteria are stricter, they often apply a higher interest coverage requirement, and many have limited appetite for portfolios, HMOs, or limited company lending.

Specialist buy-to-let lenders are built for the cases mainstream lenders find difficult: portfolio landlords, limited companies, HMOs, multi-unit freehold blocks, and more complex situations. Rates are usually a little higher, but criteria are far more flexible, and this is where most landlords beyond a simple single let end up. Many specialist lenders are intermediary-only, which means you can only reach them through a broker.

Complex and short-term lenders handle adverse credit, non-standard construction, heavy refurbishment, and bridge-to-let strategies. They are the most flexible and the most expensive, and suit deals that do not fit anywhere else.

Knowing which type your case belongs to is most of the work. It narrows the field before you look at a single rate.

The criteria that decide fit

These are the things that actually determine whether a lender will lend to you, and how much. They change far more slowly than rates, which is why they are the right place to focus.

Maximum loan-to-value. Most buy-to-let lenders cap at 75%, some reach 80%. The higher the LTV you need, the fewer your options and the higher your rate.

Interest coverage ratio and stress testing. Buy-to-let affordability is assessed mainly on rental income. The rent has to cover the mortgage interest by a set ratio, commonly around 125% for limited company and basic-rate borrowers and 145% for higher-rate taxpayers, tested at a stressed rate above the pay rate. This sets your maximum loan, and it varies significantly between lenders, so two lenders on a similar rate can offer very different amounts.

Fees versus rate. Compare the total cost over your fixed period, not the headline rate. A low rate with a large percentage fee can cost more than a higher rate with a flat or no fee, especially on larger loans.

Early repayment charges. Buy-to-let products often carry charges for two to five years, and they can be substantial. They matter if you might sell or refinance before the fix ends.

Limited company lending. Not every lender lends to a limited company or SPV. Specialist lenders generally do, usually at a small premium over personal rates, which is why many landlords buying through a company gravitate to them.

Portfolio landlord rules. If you have four or more mortgaged buy-to-let properties you are a portfolio landlord, and since 2017 lenders must assess your whole portfolio, not just the property being financed. Some lenders welcome large portfolios, others cap their exposure, so this alone can decide who will lend.

Specialist property appetite. HMOs, multi-unit freehold blocks, holiday lets, and non-standard construction are outside many mainstream lenders’ criteria. Specialist lenders have genuine appetite for them, often with dedicated products.

EPC and property condition. Energy efficiency and condition increasingly feed into both lending decisions and valuations, and standards are tightening, so they are worth factoring in early.

How to choose for your situation

Match your situation to the right type of lender first, then shortlist.

First-time landlord with a simple single let. Mainstream lenders offer the sharpest rates, so start there, provided you meet their criteria.

Portfolio landlord. With four or more mortgaged properties you need lenders built for portfolio underwriting, which points to the specialists.

Buying through a limited company. You need lenders with a proper limited company range, which is most specialists and a growing number of mainstream lenders.

HMO, multi-unit, or specialist property. You need lenders with genuine appetite for the specific property type, not a mainstream bank that will decline it.

Complex, adverse, or non-standard. You need the complex and short-term lenders, and should expect to pay more for the flexibility.

Why most landlords use a broker

Here is the part the ranked lists tend to underplay. Many of the strongest buy-to-let lenders, particularly the specialists, are intermediary-only, which means you cannot approach them directly at all. You can only reach them through a mortgage broker.

A whole-of-market buy-to-let broker pulls live products across the market, knows each lender’s criteria in detail, and matches your case to the lenders who will actually lend, which saves declined applications and wasted time. Because buy-to-let is so criteria-driven and rates move so quickly, choosing a lender is, in practice, often about choosing a good broker to access the market on your behalf. Both the comparison sites and the lenders themselves generally give the same advice.

The 2026 context

A few things shape the market you are borrowing into. Rates are higher than landlords were used to a few years ago. The restriction of mortgage interest relief to the basic rate for individual landlords has made limited company structures more common. There is a stamp duty surcharge on additional property, currently 5%, to factor into any purchase. Portfolio landlords face the whole-portfolio underwriting described above. And the Renters’ Rights Act, in force since May 2026, has changed how tenancies work. None of these change how to choose a lender, but they change the maths around the decision.

The mistake to avoid

The most common mistake is chasing whoever tops a comparison table this week. Rankings date quickly, and the cheapest headline rate is worthless if the lender will not lend on your case. A better approach is to identify two or three lenders, or lender types, that genuinely fit your deal, then let a broker pull the live products for those names rather than applying to whoever looks cheapest today.

Frequently asked questions

Which is the best buy-to-let lender?
There is no single best lender. The right one depends on your situation: mainstream lenders for simple single lets, specialist lenders for portfolios, limited companies, and HMOs. Match the lender to your case rather than to a ranking.

Do I need a broker to get a buy-to-let mortgage?
Not legally, but many buy-to-let lenders are intermediary-only, so you cannot reach them directly. A whole-of-market broker will find the lenders that fit your case, which is why most landlords use one.

Can I get a buy-to-let mortgage through a limited company?
Yes. Most specialist lenders and a growing number of mainstream lenders offer limited company or SPV lending, usually at a small premium over personal rates.

What is the interest coverage ratio?
It is the ratio by which your rental income must cover the mortgage interest at the lender’s stressed rate, commonly around 125% to 145%. It is the main thing that sets your maximum loan.

What is a portfolio landlord?
A borrower with four or more mortgaged buy-to-let properties. Since 2017, lenders must assess the whole portfolio when you apply, so portfolio landlords are underwritten more thoroughly.

Which lenders are best for HMOs?
Specialist lenders with genuine appetite for HMOs, rather than mainstream banks, which often will not lend on them. The right choice is decided by the property type, not by a general ranking.

The takeaway

The best buy-to-let lender is the one that will lend on your property, at the loan you need, at a sensible total cost, not whoever is cheapest on a table this week. Work out your situation, match it to the right type of lender, and use a broker to access the market, especially the specialist lenders you cannot reach directly.