Section 24 Tax Calculator: Buy-to-Let Limited Company vs. Personal Ownership

The moment that typically drives an English landlord to reconsider their entire strategy is the tax return. For higher-rate taxpayers, the full implementation of Section 24 frequently produces a situation where the tax owed on rental income exceeds the actual cash the portfolio generates. That is not a theoretical edge case — it is a documented reality for thousands of leveraged landlords operating in personal names in 2026.

What Section 24 Actually Does

Section 24 of the Finance (No. 2) Act 2015 removed the ability of individual landlords to deduct mortgage interest as an operating expense. Instead, interest costs receive a flat 20% tax credit, regardless of the landlord's marginal income tax rate.

For basic-rate (20%) taxpayers, the effect is roughly neutral — the 20% credit offsets the 20% tax on the interest. For higher-rate (40%) or additional-rate (45%) taxpayers, the mismatch is devastating.

Worked example:

A higher-rate landlord has:

• Gross annual rent: £15,000
• Mortgage interest: £5,000
• Actual operating profit: £10,000

Under the old rules, taxable income was £10,000. Tax at 40% = £4,000.

Under Section 24, taxable income is the full £15,000. Tax at 40% = £6,000, minus the 20% credit (£5,000 x 20% = £1,000) = net tax bill of £5,000.

That is a 50% effective tax rate on actual commercial profit of £10,000.

If interest rises to £8,000:

• Actual profit: £7,000
• Tax: (£15,000 x 40%) - (£8,000 x 20%) = £6,000 - £1,600 = £4,400
• Effective tax rate on actual profit: 62.8%

The secondary effect is equally damaging: taxing gross rent rather than net profit artificially inflates total income. This can push a landlord above the £100,000 threshold at which the personal allowance starts being withdrawn (at a rate of £1 for every £2 over the threshold, creating an effective marginal rate of 60% on income in that band), or cause Child Benefit to be clawed back.

Why a Limited Company (SPV) Fixes the Section 24 Problem

A limited company is not subject to Income Tax. It pays Corporation Tax on net profits. Crucially, a company operates under commercial accounting rules: 100% of mortgage interest is deductible as a legitimate business expense before any tax is calculated.

Corporation Tax rates for 2026/2027:

• 19% on profits up to £50,000 (small profits rate)
• 25% on profits above £250,000 (main rate)
• Marginal relief between £50,000 and £250,000

For the same landlord in the example above, operating through a limited company:

• Gross rent: £15,000
• Mortgage interest deducted: £5,000
• Taxable profit: £10,000
• Corporation Tax at 19% (small profits rate): £1,900

The company retains £8,100 for reinvestment. To extract profits personally, the director receives dividends. After the £500 annual dividend allowance, dividends are taxed at 10.75% (basic rate), 35.75% (higher rate), or 39.35% (additional rate).

The SPV structure is decisively superior for landlords who are portfolio builders — those retaining earnings within the company to compound and fund further purchases. It is less clear-cut for landlords who need immediate personal income extraction, where the double taxation layer (Corporation Tax followed by dividend tax) must be modelled carefully.

The Problem with Transferring Existing Properties to a Limited Company

If you already own properties in your personal name, incorporation is not a simple administrative change — it is a disposal triggering a cascade of tax events.

Capital Gains Tax (CGT). HMRC treats the transfer as a sale at open market value. CGT applies at 18% (basic rate) or 24% (higher rate) on the gain above the £3,000 annual exemption. For properties held through decades of capital growth, this liability can be substantial and entirely unfunded — there are no actual sale proceeds to fund the bill.

SDLT. The acquiring company must pay Stamp Duty Land Tax at the additional property surcharge rates (5% on the first £125,000, 7% on £125,001 to £250,000, 10% on £250,001 to £925,000). For a £300,000 property, that is approximately £23,750 in SDLT alone.

Mortgage redemption. Existing personal mortgages cannot transfer to the company. They must be redeemed, potentially triggering Early Repayment Charges. The company then needs new corporate financing at typically higher rates.

Legal costs. Dual-representation legal fees, RICS valuations, and broker arrangement fees typically add a further £2,000 to £5,000 per property.

Section 162 Incorporation Relief

One statutory mechanism exists to defer the CGT on transfer: Section 162 of the Taxation of Chargeable Gains Act 1992. It allows landlords to roll the capital gain into the base cost of newly issued company shares, deferring rather than eliminating the CGT.

HMRC conditions for Section 162 are strict. The portfolio must be operated as a genuine business rather than a passive investment. The HMRC-accepted benchmark is typically 20 or more hours per week actively managing the portfolio. Passive investors with two or three properties managed entirely by an agent are unlikely to qualify.

Even if Section 162 applies, SDLT is still payable by the acquiring company unless a complex partnership incorporation structure (typically via an LLP) is used — a specialist tax lawyer's territory, and heavily scrutinised by HMRC.

How to Set Up a Buy-to-Let Limited Company

For investors purchasing their first or next property, starting fresh in a corporate structure avoids the transfer problem entirely.

The standard approach is:

1. Incorporate a Special Purpose Vehicle (SPV) with SIC code 68100 (Buying and selling of own real estate) or 68209 (Other letting and operating of own or leased real estate).
2. The company applies for a buy-to-let mortgage in its own name. Most major lenders now offer corporate BTL products; directors are typically required to provide personal guarantees.
3. Properties are purchased and titled in the company's name from the outset.

Mortgage product availability has expanded significantly as the SPV market has grown to approximately 75% to 80% of new buy-to-let purchases. The rate differential between personal and corporate mortgages has narrowed considerably in the last two to three years.

Is a Limited Company Right for Your Situation?

The honest answer is: it depends on the numbers. The key variables are your marginal tax rate, how much you need to extract personally versus retain for reinvestment, the number of properties you hold or plan to acquire, and whether you are incorporating an existing portfolio (triggering transfer costs) or starting fresh.

For a higher-rate taxpayer planning to hold three or more properties for the long term, the Corporation Tax saving over ten years typically far exceeds the upfront incorporation costs. For a single accidental landlord who inherited a property and wants minimal involvement, the administration overhead and professional accounting fees may not be worth the tax saving.

The England Property Investment Guide includes a worked decision framework covering SDLT transfer costs, Section 162 qualification criteria, dividend extraction modelling, and ICR stress test comparisons for personal versus corporate borrowing — the inputs you need before commissioning an accountant to confirm the numbers.

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