Buy-to-Let Mortgages Explained: Rental Cover, Deposits and Tax

This guide provides general information and is not a substitute for personalised mortgage, tax or legal advice.

Written and reviewed by the Highhouse Money mortgage team · Last reviewed: 25 August 2026

Buy-to-let mortgages are assessed differently from residential ones. Instead of focusing mainly on your personal income, lenders look closely at the rental income the property is expected to generate, testing whether it comfortably covers the mortgage interest even if rates rise or the property stands empty for a while.

This guide walks through how that assessment works, the choice between owning a property personally or through a limited company, and the practical and tax questions worth raising with your advisor and accountant before you commit.

Buy-to-let starting checklist

Work out your likely deposit — often from 25% upward depending on the lender
Get a realistic rental valuation for the property, not just an asking price
Understand the interest cover ratio (ICR) and stress rate the lender will apply
Decide whether personal or limited company ownership suits your position
Speak to an accountant about tax treatment before you exchange
Budget for void periods, maintenance, letting agent fees and landlord insurance
Check whether the mortgage will be regulated or unregulated for your situation
Consider how the purchase fits any wider portfolio or long-term plans

How buy-to-let lending is assessed

Rather than relying primarily on your salary, buy-to-let lenders typically calculate the maximum loan by reference to the expected rental income. They apply an interest cover ratio — commonly requiring rent to exceed the mortgage interest by a set margin — calculated at a stress rate that is usually higher than the actual pay rate, to build in a buffer against future rate rises.

This means the rental valuation the surveyor provides can matter as much as the purchase price when it comes to how much you can borrow. A property with strong rental demand relative to its price will usually support more borrowing than one with high value but modest achievable rent.

Deposits and loan-to-value

Buy-to-let deposits are usually larger than for a residential purchase, and the maximum loan-to-value available can depend on the property type, the rental cover calculation and your personal circumstances, including whether you are a first-time landlord or already hold other rental properties.

Some buy-to-let and commercial mortgages are not regulated by the Financial Conduct Authority. Consumer buy-to-let arrangements, where you or a family member have lived in or intend to live in the property, can be regulated — ask your advisor which category applies to your purchase.

Personal ownership versus limited company

	Personal ownership	Limited company (SPV)
Tax on rental profit	Income tax at your marginal rate	Corporation tax on company profit
Mortgage interest relief	Restricted for individual landlords	Can typically be offset as a business expense
Mortgage rates and fees	Often a wider choice of products	Can carry different pricing and fewer lenders
Extracting profit	Straightforward — it is already yours	Usually via dividends or salary, with further tax
Suits	Smaller portfolios, basic-rate taxpayers	Larger portfolios, higher-rate taxpayers, long-term holds

This is a simplified comparison. The right structure depends on your wider tax position — get advice from an accountant alongside your mortgage advisor.

Understanding the running costs, not just the mortgage

Landlord insurance suited to a rented property, not a standard home policy
Letting agent fees if you use one to manage tenants and maintenance
Gas safety, electrical and other statutory compliance checks
Maintenance and repair reserves, particularly for older properties
Void periods where the property earns no rent but the mortgage still falls due

Tax considerations landlords commonly face

Buying a second or subsequent residential property usually attracts a Stamp Duty Land Tax surcharge, rental income is subject to income tax or corporation tax depending on ownership structure, and selling the property can trigger Capital Gains Tax. Rules in this area have changed materially in recent years and continue to evolve, so this guide gives a general picture only — always check current HMRC guidance and take personalised tax advice.

Portfolio landlords and specialist scenarios

If you already own four or more mortgaged buy-to-let properties, you are generally treated as a 'portfolio landlord', and lenders will usually want to assess your whole portfolio's finances, not just the single property being mortgaged. HMOs, multi-unit blocks and holiday lets are also treated differently again — see our dedicated guides linked below.

What lenders may assess

Expected rental income, usually confirmed by an independent valuation
Interest cover ratio against the mortgage interest at a stress-tested rate
Deposit and resulting loan-to-value
Your personal or company financial position and credit history
Whether you are a first-time landlord or already own rental property
Property type, condition and any specialist features such as HMO or new-build status
For portfolio landlords, the overall performance and gearing of the wider portfolio

Every lender sets its own criteria, which change regularly. The points above are common themes, not a guarantee of how any individual lender will treat an application.

Frequently asked questions

How much deposit do I need for a buy-to-let mortgage?

Buy-to-let deposits are typically larger than for residential mortgages, often starting around 25% of the property's value, though this varies by lender and property type. The exact figure available to you depends on the rental income, your circumstances and the lender's criteria at the time.

What is rental cover or ICR?

The interest cover ratio (ICR) is a calculation lenders use to check that the expected rental income covers the mortgage interest by a comfortable margin, often tested at a notional 'stress rate' higher than the actual pay rate. This protects against rate rises or void periods, but it also means the amount you can borrow is driven by rental income, not just your personal income.

Can I get a buy-to-let mortgage as a first-time landlord?

Some lenders will consider first-time landlords, and some will lend to first-time buyers taking on a buy-to-let, but many require you to already own your own home or have prior letting experience. Availability depends on the lender's criteria and your overall circumstances.

Should I buy in my personal name or a limited company?

Both are common structures with different tax and mortgage implications. Personal ownership can mean simpler mortgage criteria but income tax on rental profit and restricted mortgage interest relief for higher-rate taxpayers. Limited company ownership pays corporation tax on profit and can retain full relief on mortgage interest, but company buy-to-let mortgages can carry different rates and fees. This is a decision to make with an accountant alongside your mortgage advisor.

Are buy-to-let mortgages regulated by the FCA?

Most buy-to-let mortgages are not regulated in the same way as residential mortgages because they are treated as a business or investment activity, though 'consumer buy-to-let' arrangements — broadly, where the landlord or a family member has lived in the property, or plans to — can fall under FCA regulation. Some buy-to-let and commercial mortgages are not regulated by the Financial Conduct Authority; check the status of your specific arrangement with your advisor.

What tax do landlords pay on rental income?

Landlords pay income tax (personal ownership) or corporation tax (limited company ownership) on rental profit, and may also face Stamp Duty Land Tax surcharges on purchase and Capital Gains Tax on sale. Tax rules for landlords have changed significantly in recent years, including the phasing out of full mortgage interest relief for individual landlords. Always get current, personalised tax advice from an accountant or HMRC guidance — this guide does not constitute tax advice.

What happens if my property is empty between tenants?

You remain responsible for the full mortgage payment regardless of whether the property is let. Most lenders and advisors recommend landlords budget a contingency for void periods, maintenance and unexpected repairs rather than relying on rent covering costs every single month.

Can I remortgage a buy-to-let property to raise money?

Many landlords remortgage to release equity for further purchases, renovations or other purposes, subject to the lender's rental cover and loan-to-value criteria at the time. The same stress-tested rental calculations apply as for a new purchase.

Do I need landlord insurance as well as a mortgage?

Standard home insurance is not designed for rented property. Lenders typically require buildings insurance appropriate to a let property, and most landlords also arrange contents, liability and rent-guarantee cover suited to their situation.

Sources and further reading

Where figures or rules can change, the position described is correct at the time of writing (25 August 2026) — always check the linked authoritative source for the latest position.

Buy to Let mortgages

Whole-of-market advice for personal and limited company landlords.

Limited company buy to let

How SPV mortgages work and when they can make sense.

HMO and multi-unit mortgages

Specialist finance for houses in multiple occupation and blocks of flats.

Residential mortgages

If you're moving from renting out to buying your own home, or vice versa.

Commercial mortgages

For larger or mixed-use property investments.

Talk to a landlord specialist

Tell us about the property and we'll talk through the options.

Talk it through with an advisor

Every case is different. A short, no-obligation conversation with a whole-of-market advisor is often the fastest way to understand your options. Call 0345 512 0077 or send us a message.

Contact an advisor