Landlord Tax Calculator (2026/27)

Get your rental portfolio - and its tax - under control

Being a landlord has never been more of an admin job. Between tracking rent across several properties, logging every allowable expense, and getting to grips with the Section 24 mortgage-interest rules that quietly pushed many landlords into a higher tax bill, it's easy to lose sight of how much you're really making after tax. This free organiser pulls it together: add each of your properties, enter the income, expenses and mortgage interest, and see your taxable profit, your Section 24 tax credit and your estimated tax - both per property and across the whole portfolio.

Specialist landlord software exists, but it's almost always a paid subscription. For a landlord with one or two properties, that's hard to justify just to keep a tidy record and estimate the tax. Our organiser does the core job for free, saves everything privately in your browser, and exports a CSV you can pass straight to your accountant or use to fill in your Self Assessment return.

How rental income is taxed

Rental profit is taxed as part of your income, on top of any salary, pension or self-employment earnings. In simple terms, your taxable rental profit is your rental income minus your allowable expenses. Allowable expenses include things like letting agent and management fees, repairs and maintenance (but not improvements), landlord insurance, ground rent and service charges, council tax or utilities you pay, and accountancy fees. What you cannot deduct in the old way is mortgage interest - and that's where Section 24 comes in. HMRC's guidance on paying tax when you rent out a property sets out the framework in full.

Section 24: the rule that changed buy-to-let

Until a few years ago, landlords could deduct mortgage interest from their rental income before working out the tax, just like any other expense. Section 24 ended that. Phased in between 2017 and 2020, it means mortgage interest is no longer deductible from your rental profit. Instead, you get a tax credit worth 20% of the interest - the basic rate. For basic-rate taxpayers the effect is broadly neutral, but for higher and additional-rate landlords it's a real increase in tax, because their profit is now taxed at 40% or 45% while the relief on interest is capped at 20%.

This organiser applies Section 24 correctly: it does not deduct mortgage interest from your profit, and instead works out the 20% credit (capped at your profit). You choose your top tax band so the estimate reflects whether you're a basic, higher or additional-rate taxpayer. To see the impact of the rule on a single property in more detail, our dedicated Section 24 Calculator breaks it down, and the Rental Income Tax Calculator gives a fuller single-property view.

How to use the organiser

Add each property in turn: give it a name or address, enter the annual rental income, the allowable expenses (excluding mortgage interest), and the mortgage interest only - not the capital repayment, which isn't relevant for tax. Pick your top tax band at the top. The portfolio summary then shows your total income, taxable profit, estimated tax and after-tax income, with a per-property breakdown in the table below. Everything recalculates instantly as you add or remove properties.

Because your data is saved in your browser, you can build the picture up over the year and come back whenever a new expense crops up. Export a CSV at year end - or whenever you meet your accountant - and you've got a clean, itemised record. If you clear your browser or switch devices the data won't follow you, so an occasional CSV export is a sensible backup.

A note on what the estimate covers

This is a portfolio estimator, not a full personal tax return. It estimates tax on your rental profit at the marginal band you select, because it doesn't know your other income or your Personal Allowance. In practice, rental profit stacks on top of your other income, so part of it might fall in a higher band than you expect - particularly if your salary already uses up the basic-rate band. For most landlords the band-based estimate is close enough for planning; for the final figure, your Self Assessment return (or your accountant) is definitive.

Making Tax Digital is coming for landlords too

If your combined property and self-employment income is high enough, you'll soon need to keep digital records and send HMRC quarterly updates under Making Tax Digital for Income Tax. Landlords with gross property income over £50,000 were brought in from April 2026, with lower thresholds following. Use our MTD Scope Checker to see whether and when it applies to you, and the MTD Quarterly Record Organiser to keep the digital records you'll need. Remember the threshold is based on gross rent, not profit - so even a heavily mortgaged portfolio can be in scope.

Other tools landlords find useful

Tax is only one part of running a profitable rental business. When you're weighing up a new purchase, the Rental Yield Calculator shows the return on the price you'd pay, and the Buy-to-Let Mortgage Calculator helps you compare financing. At purchase you'll usually pay the higher rate of stamp duty on an additional property - work it out with the Stamp Duty Calculator (or the LBTT Calculator in Scotland and the LTT Calculator in Wales). And for day-to-day paperwork, our free Rent Receipt Generator produces clean receipts for tenants in seconds.

Keeping good records pays off

The landlords who find tax season painless are the ones who log income and expenses as they go, keep the paperwork, and never let a year's worth of transactions pile up. Beyond saving stress, good records make sure you claim every allowable expense - and missed expenses are missed tax savings. A few minutes adding a repair bill or an insurance premium here keeps your taxable profit accurate and your eventual bill as low as it legitimately can be.

For the official rules on expenses, allowances and the tax treatment of different letting arrangements, HMRC's guidance for property income and the property pages on GOV.UK are the authoritative reference. Use them for the detail, and this organiser for the running record and the day-to-day estimate.

The bottom line

Section 24, Making Tax Digital and rising costs have made landlord admin more demanding than ever, but the answer isn't an expensive subscription - it's a clear, consistent record and a realistic view of your tax. This organiser gives you both, free and private, across as many properties as you own. Add your first property above, pick your tax band, and see exactly where your portfolio stands after tax.

A worked Section 24 example

Numbers make Section 24 much clearer. Imagine a higher-rate landlord with £18,000 of rent, £4,000 of allowable expenses (excluding mortgage) and £6,000 of mortgage interest. Under the old rules, taxable profit would have been £18,000 − £4,000 − £6,000 = £8,000, taxed at 40% = £3,200. Under Section 24, the £6,000 interest is no longer deducted, so taxable profit is £18,000 − £4,000 = £14,000, taxed at 40% = £5,600 - but you then get a 20% credit on the £6,000 interest, worth £1,200. The final tax is £5,600 − £1,200 = £4,400. That's £1,200 more than under the old system, purely because of how the interest is treated. This organiser applies exactly that logic across every property you add.

For a basic-rate landlord the difference largely washes out, because the relief and the tax rate are both 20%. The sting falls on higher and additional-rate landlords, and on basic-rate landlords whose rental profit tips them into the higher band once it's added to their other income. That tipping-point effect is the subtle part of Section 24 that catches people out, and it's why seeing the whole portfolio in one place matters.

Joint ownership, holiday lets and other situations

If you own a property jointly - with a spouse, for example - the income and expenses are normally split according to ownership, and each owner reports their share. Couples sometimes use a different split via a formal declaration, which can be tax-efficient if one partner is a lower earner; it's worth taking advice before doing this. Furnished holiday lets used to have their own favourable rules, but those have been abolished, so most short-term lets are now treated like ordinary rental property. And the Rent-a-Room scheme can make letting a room in your own home tax-free up to a generous threshold. For the authoritative detail on all of these, HMRC's guidance on working out your rental income is the place to check.

Whatever your situation, the principle is the same: keep clear records, claim every legitimate expense, and understand how the mortgage-interest credit affects you. Use this organiser through the year, lean on the Section 24 Calculator for the detail on a single property, and bring an accountant in for anything unusual. Good records make their job - and your tax bill - smaller.