Put one buy-to-let purchase through the numbers: the stamp duty, the yield, the cash flow after the mortgage, and the tax — owning it personally under the Section 24 rules, or through a limited company. Enter the price, the loan, the rent and the running costs; the analyser shows every line of its working. It gives figures, not a verdict: whether a deal is worth doing is your call.
Your figures stay in your browser: nothing you type is sent to us or stored. We count only that the page was opened and that a calculation was run — how we count.
Tax years. The calculation uses the current tax year, 2026 to 2027, unless you choose otherwise. You can also choose the next tax year, which starts in April 2027: from then, rental profit is taxed at new property income rates of its own Announced, not yet lawAnnounced at Autumn Budget 2026, to be legislated in Finance Bill 2026-27. Those rates apply to property income only; they do not change the income tax on earnings or pensions. Savings income has its own savings rates, which the same Budget also raises from that date, and dividend income has separate rates; this tool covers neither. Stamp duty is worked out for England and Northern Ireland.
How the analyser works it out
It follows the money through one year. The rent for twelve months, less your void allowance, is the rent collected. Letting and management fees, maintenance, insurance, service charge and any other running costs come off that to give the net operating income — what the property earns before finance and tax. The net yield is that figure divided by the price; the gross yield is the full year's rent divided by the price. Mortgage payments then come off to give the cash flow before tax.
The cash you put in is the deposit plus stamp duty plus your other purchase costs. Stamp duty is calculated from the same bands as our stamp duty calculator: the higher rates for an additional dwelling once the price reaches £40,000, and always the higher rates in the company column.
Owning it personally: Section 24
As an individual landlord you cannot deduct mortgage interest from your rental profit. Instead the whole profit is taxed at your income-tax band's rate, and you get a tax reduction worth the basic rate — 20% for 2026 to 2027, 24% for 2027 to 2028 (announced, not yet law) — on the lowest of three amounts: your finance costs, your property profit, and your income above the personal allowance. Any finance costs left over carry forward. The analyser shows the extra tax this rule costs you against the old treatment, where interest came straight off profit.
Income-tax band
2026 to 2027
2027 to 2028 (from April 2027; announced, not yet law)
Basic rate
20%
24%
Higher rate
40%
44%
Additional rate
45%
49%
2026 to 2027: Ordinary income-tax rates — Tax year 2026-27 (6 April 2026 to 5 April 2027). 2027 to 2028: Property income rates — Tax year 2027-28 onward (6 April 2027); applied to property income, not to other income. Announced at Autumn Budget 2026, to be legislated in Finance Bill 2026-27. The rate the analyser uses is the one for the band you pick, in the year you pick, applied to the whole rental profit.
Owning it through a limited company
A company deducts its finance costs in full and pays corporation tax on what is left: 19% on profits up to £50,000, 25% from £250,000, with marginal relief at a fraction of 3/200 in between. Those limits are divided between associated companies. The company column is company level, before extraction: profit left in a company is not money you hold, and paying it out to you is taxed again. Enter a dividend tax rate to see what would reach you.
Worked example
These figures were produced by running this page's own calculator on the rates shown here, so they move when the rates do.
A higher-rate taxpayer buys a £200,000 flat as an additional property with a £50,000 deposit and an interest-only mortgage at 5% a year. It lets for £1,100 a month. Allowing 4% for voids, 10% for management, £600 for maintenance and £300 for insurance:
Stamp duty (higher rates)
£11,500
Cash invested (deposit, stamp duty, other purchase costs)
£63,500
Gross yield
6.60%
Net yield
5.25%
Net operating income
£10,504.80
Mortgage interest
£7,500
Cash flow before tax (a year)
£3,004.80
Income tax at 40%, before the Section 24 reduction
£4,201.92
Section 24 reduction
£1,500
Cash flow after tax, owned personally
£302.88
Corporation tax, owned through a company
£570.91
Cash left in the company
£2,433.89
Section 24 costs this landlord £1,500 a year compared with deducting the interest in full. At the stress-test rate of 7%, the cash flow before tax would be £4.80 a year.
The same purchase in the next tax year, on the property income rates announced for April 2027 (not yet law): income tax before the reduction rises to £4,622.11 at 44%, the reduction becomes £1,800 at 24%, and the cash flow after tax is £182.69. The company column does not change, because corporation tax is not affected.
Common mistakes
Comparing your net yield with someone else's gross yield. The analyser shows both so you can compare like with like.
Reading the company column as money in your pocket. It is cash inside the company until it is paid out, and paying it out is taxed again.
Forgetting that capital repaid on a repayment mortgage is not a finance cost. Only the interest counts towards the Section 24 reduction.
Leaving out voids and maintenance. A cash flow with no allowance for either describes a year that rarely happens.
Rates used, and where they come from
Rates checked against their sources on 29 October 2026; due to be re-read by 27 January 2027. They are the same table the UK Property Portal members area uses.
Income tax is worked out at the single rate for the band you pick, applied to the rental profit. If your rental profit straddles two bands the real figure differs.
Scottish income-tax rates, and the Scottish and Welsh property rates their Parliaments may set, are not modelled.
The flat 17% SDLT rate that can apply to a company buying a dwelling over £500,000, the reliefs from it, and the surcharge for non-UK residents are not modelled — enter your own SDLT figure to override the calculation.
Capital allowances, replacement-of-domestic-items relief, losses carried forward and the corporate interest restriction are not modelled.
Company profit left in the company is not your money: the company column is company level, before extraction, unless you give a dividend tax rate.
Questions
Is it better to buy a rental through a limited company?
The analyser does not say, because the answer depends on things it cannot see: whether you need the income personally, your other income, how long you will hold the property, and the costs of running a company. It shows both columns side by side so you can see the difference on your own figures. The company column is before extraction; enter a dividend rate to see what would reach you.
What changes for landlords in the next tax year?
From the tax year starting in April 2027, rental profit is taxed at new property income rates: 24%, 44% and 49% for the basic, higher and additional bands, and the Section 24 reduction is given at the property basic rate of 24%. Status of these rates: Announced at Autumn Budget 2026, to be legislated in Finance Bill 2026-27; they are not yet law. The change applies to property income only, not to earnings or pensions. Choose that tax year in the form to see its effect.
Why does the analyser use only the first year's mortgage interest?
Section 24 relief is worked out on the finance costs of the tax year, and the analyser looks at one year. On a repayment mortgage it uses the interest in the first twelve payments; the capital you repay is not a finance cost and gets no relief.
Does it include capital growth or a sale?
No. It is one year of income and tax, with no rent growth, no change in the property's value and no sale. For tax on a sale, use the capital gains tax calculator.
An estimate worked out from the figures you enter. It is not financial or tax advice; check your own case against the guidance linked on this page, or with an adviser, before you act on it.