Buy-to-let analyser
The buy-to-let calculator that follows a rental property all the way through tax — yield, monthly cashflow, the lender interest-cover test, and whether to hold it personally or through a limited company. Then project the whole hold, capital gain and all.
The deal
Rent & running costs
Cashflow — first year
Cash needed up front
The property’s location sets the purchase tax — SDLT with the 5% surcharge, LBTT with the 8% Additional Dwelling Supplement, or the LTT higher rates. Income tax on the rent uses rest-of-UK bands.
Tax
Personal vs limited company, as you scale
The same deal, repeated across a portfolio. Because personal profit stacks on your income while a company is taxed on its own, the gap usually widens the more you own.
Why the company usually wins at scale
Project the whole hold
Equity builds from price growth; rental profit accumulates after tax each year. On sale you repay the mortgage and pay Capital Gains Tax (personal) or corporation tax on the gain (company).
What Section 24 did to the personal landlord
Since 2020, individual landlords no longer deduct mortgage interest from rental profit. Instead the whole rent is taxed and a 20% credit comes back on the interest, which is neutral for basic-rate taxpayers and a genuine squeeze for higher-rate ones, since relief arrives at half their tax rate. On this page's default deal, a £200,000 property with £1,200 rent and a 5.5% mortgage, a £45,000-a-year owner clears £93 a month after tax. The same deal inside a limited company, where interest remains fully deductible against Corporation Tax, clears £193. That gap is Section 24 in a single line.
Company ownership has its own bill
Before switching everything into a company, note what the comparison hides: company profits still need extracting, and dividend tax on the way out erodes the advantage for landlords who spend the rent rather than reinvest it. Company mortgages also price higher, and moving an existing personal property in means selling it to the company, with CGT and stamp duty on the transfer. The structure decision deserves its own sums per property, which is exactly what the ownership toggle above is for.
Stress tests and the deal that works on paper
Lenders test that rent covers the mortgage with headroom, typically 125% to 145% at a stressed rate, and the verdict panel checks your figures against a typical test. Voids, management, maintenance and insurance all sit in the running costs here because deals that ignore them look brilliant right up until February. Check the headline return against the rental yield calculator, price the purchase tax with the stamp duty calculator including the 5% surcharge, and if the money might work harder elsewhere, the property vs investing comparison is the honest referee.
Common questions
Is buy-to-let still worth it in 2026?
It can be, but the margins are thinner than they were. Higher mortgage rates and Section 24 — which stops individual landlords deducting mortgage interest from rental profit — mean many geared deals now make only a small monthly profit, or a loss, on rent alone. The case increasingly rests on capital growth and on buying well. The analyser shows the after-tax cashflow so you can see whether a specific deal actually stacks up.
What is Section 24 and how does it affect landlords?
Section 24 is the rule that removed mortgage-interest relief for individual landlords. Instead of deducting interest as a cost, you pay income tax on the full rental profit and then get a flat 20% tax credit on the interest. For a higher-rate taxpayer that means being taxed at 40% on profit you never really keep, and the extra income can even tip you into a higher band. Companies are not affected — they still deduct interest in full.
Should I buy a rental property through a limited company?
A company can deduct all its mortgage interest and pays 19% corporation tax on the first £50,000 of profit, so it often keeps more than a higher-rate individual landlord — especially when you are scaling a portfolio and reinvesting. The catch is that taking the money out as dividends is taxed again, and companies face higher mortgage rates and running costs. The analyser compares the two side by side as you add properties.
What is the ICR or buy-to-let stress test?
Interest Cover Ratio is the test buy-to-let lenders apply: the rent must cover the mortgage interest by a set margin — commonly 125% for companies and basic-rate borrowers, and around 145% for higher-rate individuals — usually calculated at a stressed interest rate rather than your actual pay rate. If the rent falls short you may need a larger deposit or a lower rate. The analyser flags whether your rent clears a typical stress test.
These results are estimates for general information only and are not financial advice. Buy-to-let is a leveraged, illiquid investment and the tax treatment is complex — check every figure and take appropriate professional advice before acting. Read the full disclaimer.