Do I need a business plan for a buy-to-let mortgage?

For a single property, usually not. Once you have four or more mortgaged buy-to-let properties, lenders assess your whole portfolio under Prudential Regulation Authority rules and will often ask for a business plan, cash flow forecast and property schedule.

What is a good rental yield in the UK?

Gross yields vary widely by area, from low single figures in expensive parts of London and the South East to considerably higher in some northern towns. Gross yield ignores costs, so judge a property on the net return after agent fees, repairs, voids, finance costs and tax.

Should I buy a rental property in a limited company?

It depends on your tax rate, whether you will reinvest the profit, and how many properties you plan to hold. A company can deduct mortgage interest but pays tax again when money is taken out. Model both routes, and take specific tax advice before buying.

How does the interest cover test work?

The lender takes the expected monthly rent and divides it by the monthly interest on the mortgage at a stressed interest rate. The result must usually be at least 125% or 145% depending on your tax position and whether you borrow personally or through a company.

What changed for landlords in 2026?

In England, the Renters' Rights Act 2025 ended section 21 no-fault evictions from 1 May 2026 and made tenancies periodic, with rent increases limited to once a year. Separately, property income tax rates rise by two percentage points from April 2027 in England, Wales and Northern Ireland.

By industry

Buy-to-Let Business Plan

Rental property looks simple on paper: buy it, let it, collect the rent. The plan is where that falls apart or holds up, because the margin between rent and costs is thinner than most first-time landlords expect once tax, voids, repairs and interest are counted. This guide covers the figures a buy-to-let lender tests, the tax choice that shapes the whole model, and the rules that changed in 2026.

Start your plan View the demo

Written by Clive Unitt FCA, Founder & Chartered Accountant

What a buy-to-let lender looks at first

A buy-to-let mortgage is assessed mainly on the property rather than your salary. The rent has to cover the interest with room to spare, at an interest rate higher than the one you will actually pay. For portfolio landlords, the lender looks at every mortgaged property together.

The interest cover test. Lenders require the rent to cover the mortgage interest by a set margin, calculated at a stressed interest rate. Commonly that is 125% for a limited company or a basic-rate taxpayer, and 145% for a higher-rate taxpayer borrowing in their own name. If the rent does not pass, the loan is reduced until it does.
The deposit and the loan-to-value. Most buy-to-let lending is capped at around 75% of the property's value, so expect to put in at least a quarter of the price, plus stamp duty and fees, from your own funds.
The portfolio as a whole, from four properties. Under Prudential Regulation Authority rules, a landlord with four or more mortgaged buy-to-let properties is a portfolio landlord. Lenders then assess the whole portfolio, its overall borrowing, rental cover and cash flow, and will often ask for a business plan and a cash flow forecast alongside the property schedule.
Evidence for the rent. A rental valuation from the lender's surveyor sets the figure used in the test, not your estimate. Base the plan on comparable lets in the same street or block, and be prepared for the valuation to come in lower.

Typical purchase and running costs

The deposit is the obvious number. The costs around it — stamp duty, fees, refurbishment and the void before the first tenant moves in — are what catch first-time landlords out.

Cost	Typical range	What drives it
Deposit	25% – 40% of price	Higher deposits unlock better rates and help pass the interest cover test.
Stamp Duty Land Tax	Standard rates plus 5%	The additional property surcharge applies to most buy-to-let purchases, in personal names and companies alike.
Mortgage arrangement and broker fees	£0 – 3% of the loan	Some products charge a percentage fee instead of a higher rate. Compare total cost over the fixed period.
Legal fees and searches	£1,500 – £3,000	Higher for a limited company purchase, leasehold property or complex title.
Survey and valuation	£400 – £1,500	The lender's valuation is not a survey. For older property, pay for a proper one.
Refurbishment and compliance	£2,000 – £40,000	Safety certificates, alarms, any works needed to meet the minimum energy standard, and whatever makes it lettable at the rent you have assumed.
Letting and management	8% – 15% of rent	A letting-only service costs less than full management. Add VAT to agents' quoted percentages.
Cash reserve	Three to six months' costs	Covers voids, repairs and mortgage payments while a property is empty.

Indicative figures for a single residential buy-to-let in England. Stamp duty depends on price and on whether you already own property; check the current rates on GOV.UK before budgeting.

The numbers that decide whether it works

These are the figures a lender turns to first, and the ones SquarePlan calculates for you as you enter your sales and costs.

Gross rental yield: The headline figure, and the least useful on its own. It ignores every cost. Use it to compare areas, not to decide whether a property makes money.
Net yield after all costs: Rent less agent fees, insurance, repairs, compliance, service charge, voids and finance costs, then less tax. This is the number that tells you whether you have an investment or an expensive hobby.
Interest cover ratio: The lender's test. Run it yourself before applying, at the lender's stress rate rather than your actual rate, so the size of loan you plan around is one you can actually get.
Void allowance: Between tenants the property earns nothing and still costs money. A forecast with twelve months' rent every year is a best case, not a plan.

The rules a landlord has to plan around

Letting residential property in England is heavily regulated, and 2026 brought the biggest change in decades. These are the rules most likely to affect the numbers. Wales, Scotland and Northern Ireland each have their own regimes.

Renters' Rights Act 2025: From 1 May 2026, section 21 no-fault evictions ended and assured shorthold tenancies were replaced by periodic tenancies. Rent can be raised once a year through a formal notice, which tenants can challenge. Plan on longer tenancies, fewer voids, and possession only on the grounds the Act allows. Further measures, including a landlord database and an ombudsman, are being introduced in stages.
Safety and compliance: A gas safety check every year, an electrical installation condition report at least every five years, working smoke and carbon monoxide alarms, deposit protection within 30 days, and Right to Rent checks. All are recurring costs and belong in the forecast.
Energy performance: A rental property needs a valid EPC and, at present, a rating of at least E. The government has proposed raising the minimum. If your property is near the line, cost the improvement works rather than assuming the rules will not change.
HMO and selective licensing: A house let to five or more people from more than one household needs a mandatory HMO licence, and many councils license smaller HMOs or all private lets in certain areas. Licence fees, room size rules and extra safety requirements all affect the return.

The margin is thinner than it looks

A property bought for £200,000 and let at £1,100 a month shows a gross yield of 6.6%, and that is the figure most listings and many first plans lead with. It is also the figure least connected to what you will actually make.

Work down from it. Agent fees, with VAT, might take a tenth of the rent. Insurance, safety certificates, repairs and a month’s void take more. Then the mortgage interest, which on a 75% loan can be the single largest cost. What is left is taxable, and if the property is in your own name and you are a higher-rate taxpayer, the restriction on mortgage interest relief means you may pay tax on money that has already gone to the lender. It is entirely possible for a property to show a 6% gross yield and lose money after tax. The plan exists to find that out before completion, not after.

Run the lender’s test before you choose the property

The interest cover test decides how much you can borrow, so run it yourself first. Take the rent you can evidence from comparable lets, the lender’s stress rate and their required ratio, and work out the largest loan the rent supports. If that loan is smaller than you need, you need a larger deposit, a cheaper property, a higher rent, or a longer fixed rate that some lenders assess at a lower stress rate. Better to know that while you are still viewing properties.

Decide on the ownership structure once, properly

Personal name or a limited company is the decision with the longest consequences, because changing it later usually means selling the property to the company, with stamp duty and possibly Capital Gains Tax to pay. The right answer depends on your other income, whether you need the rental profit to live on or will reinvest it, how many properties you plan to own, and your plans for passing them on. Model both in the plan, and take specific tax advice before you exchange contracts.

Plan for the new rules, not the old ones

The end of section 21 in England changes the economics in ways worth building in. Tenancies are likely to last longer, which can mean fewer voids and lower re-letting costs. Regaining possession now depends on specific grounds and evidence, so the cost and time of a problem tenancy is higher, and good referencing and insurance are worth more. Rent increases come once a year through a formal process, so the forecast should grow the rent on that basis rather than assume a new market rent at every change of tenant.

Where SquarePlan fits

SquarePlan asks for your rents, costs, finance and purchase costs, and builds the monthly cash flow, profit and loss and the tax calculations underneath. You can see what a higher interest rate, a longer void or a lower rent does to the cash position before you commit, and hand a lender a forecast they can follow.

How this gets funded

Most buy-to-let is funded with a mortgage and a deposit. The bigger decision is whose name the property is held in, because it changes the tax, the lenders available and how you take money out.

Personal name: Rental profit is taxed as income. Mortgage interest cannot be deducted; instead you get a tax credit at the basic rate, which hurts higher-rate taxpayers most. From April 2027, property income in England, Wales and Northern Ireland is taxed at separate rates two percentage points above the main rates.
Limited company: Mortgage interest is deductible and profit pays Corporation Tax, but taking the money out as dividends or salary is taxed again. Company mortgage rates are often a little higher. It tends to suit landlords who will reinvest profit and build a portfolio. Moving property you already own into a company usually triggers stamp duty and Capital Gains Tax.
Bridging finance: Short-term lending for auction purchases or properties that need work before a mortgage lender will accept them. Expensive, and only sensible with a clear, costed exit onto a standard buy-to-let mortgage.
Remortgaging existing property: Releasing equity from a home or another rental is a common way to fund a deposit. It increases total borrowing, and the plan should show the whole position, not just the new property.

Frequently asked questions

Do I need a business plan for a buy-to-let mortgage?: For a single property, usually not. Once you have four or more mortgaged buy-to-let properties, lenders assess your whole portfolio under Prudential Regulation Authority rules and will often ask for a business plan, cash flow forecast and property schedule.
What is a good rental yield in the UK?: Gross yields vary widely by area, from low single figures in expensive parts of London and the South East to considerably higher in some northern towns. Gross yield ignores costs, so judge a property on the net return after agent fees, repairs, voids, finance costs and tax.
Should I buy a rental property in a limited company?: It depends on your tax rate, whether you will reinvest the profit, and how many properties you plan to hold. A company can deduct mortgage interest but pays tax again when money is taken out. Model both routes, and take specific tax advice before buying.
How does the interest cover test work?: The lender takes the expected monthly rent and divides it by the monthly interest on the mortgage at a stressed interest rate. The result must usually be at least 125% or 145% depending on your tax position and whether you borrow personally or through a company.
What changed for landlords in 2026?: In England, the Renters' Rights Act 2025 ended section 21 no-fault evictions from 1 May 2026 and made tenancies periodic, with rent increases limited to once a year. Separately, property income tax rates rise by two percentage points from April 2027 in England, Wales and Northern Ireland.

Build your buy-to-let property business plan

Answer questions about your business and SquarePlan builds the projections, break-even analysis and formatted plan for you. £39.99 a month, cancel any time.

Start your plan View the demo

Clive Unitt FCA

Founder & Chartered Accountant (FCA)

Clive is a Fellow of the Institute of Chartered Accountants in England and Wales and the founder of SquarePlan. He has spent over thirty years working with businesses from sole traders to multinational public companies.

He writes here about business planning, financial projections and the UK tax and funding questions that come with starting out.

More about Clive → ICAEW member record Companies House LinkedIn

Related business plans

See every business plan guide →