The Situation: Four Properties, an Unexpected Tax Bill, and a Rethink
Marcus had been a landlord for eleven years. Four terraced houses in the East Midlands, all held in his personal name, all performing reasonably well — until the Section 24 mortgage interest relief restrictions eroded his margins to the point where his accountant delivered a bill that made him sit down twice. At his income tax rate of 40%, he was paying tax on rental income he had never actually received. The mortgage interest that used to reduce his taxable profit no longer could. He was, as his accountant put it plainly, paying tax on paper profits.
Marcus is not unusual. Thousands of landlords in the UK are sitting on portfolios built in a different tax environment, now wondering whether restructuring into a limited company makes sense — and, if they're starting fresh, how to build correctly from the outset. His story illustrates both problems and, more usefully, the mechanics of doing it right.
What Was Tried: Personal Ownership, and Why It Made Sense at the Time
When Marcus bought his first property in 2015, mortgage interest was fully deductible against rental income for higher-rate taxpayers. The logic of personal ownership was sound: simpler administration, no corporate governance obligations, and straightforward residential mortgages with competitive rates. He added properties in 2017 and 2019 using the same approach, remortgaging earlier properties to fund deposits.
The problem arrived in stages. Section 24, phased in from 2017 and fully effective by 2020, replaced full mortgage interest relief with a basic-rate tax credit. For a 40% taxpayer like Marcus, that change converted genuine cash-flow-positive properties into apparent high-profit investments — on paper — while his real net income barely moved. Each new property added to his personal tax exposure rather than building the insulated, scalable structure he needed.
He had also never separated his property activity from his personal finances. Rental income flowed into his current account. Expenses were tracked loosely. When his portfolio reached four properties, HMRC's definition of a "property business" applied — but his operational setup still looked like a hobby investor's.
The turning point came when his accountant modelled what a fifth property would do to his self-assessment bill. The answer was stark enough to prompt a structural review.
The Fix: Setting Up a Special Purpose Vehicle — and Doing It in the Right Order
Marcus's accountant and mortgage broker worked together on a plan. The core decision was to incorporate a Special Purpose Vehicle (SPV) — a limited company established specifically for property investment, using SIC code 68100 (buying and selling of own real estate) or 68209 (other letting and operating of own or leased real estate). This is the standard structure used by serious portfolio landlords in 2026.
Step 1: Incorporate the right way
The company was incorporated at Companies House with Marcus and his spouse as directors and shareholders. Shareholding was structured to use both of their basic-rate tax bands when drawing dividends — a deliberate decision, not an afterthought. The company's registered address was separate from his personal home. A dedicated business bank account was opened before any mortgage application was made. Lenders require this; some will decline if the account is new and shows no transaction history.
Step 2: Understand the mortgage landscape for limited companies
Limited company buy-to-let mortgages are assessed differently from personal-name products. Lenders underwrite against the company's rental income, the directors' personal guarantees, and — in some cases — the background portfolio. Rates are typically 0.2–0.5% higher than equivalent personal-name products, and arrangement fees can be higher. However, the tax arithmetic usually makes this cost irrelevant for higher-rate taxpayers over a five-year hold period.
For Marcus's fifth property — a three-bed semi in Nottingham — his broker approached specialist portfolio lenders who assess rental coverage at 125% of the mortgage payment at a stressed rate of 5.5%. The rental income of £1,050 per month cleared that test comfortably. He secured a five-year fixed rate and avoided the personal income tax drag entirely on that property going forward. You can explore how this applies to your own situation through buy-to-let mortgages for limited companies and portfolio landlords.
Step 3: Decide what to do with the existing personal-name properties
This is where many landlords make expensive mistakes. Transferring existing properties from personal ownership into a limited company triggers Stamp Duty Land Tax (SDLT) on market value and — potentially — Capital Gains Tax (CGT) on any gain since purchase. For Marcus, the CGT exposure on his 2015 purchase alone was over £40,000. Incorporation relief under Section 162 of the Taxation of Chargeable Gains Act 1992 can defer CGT where the activity qualifies as a business rather than passive investment, but HMRC's threshold is strict and the relief is not available to every landlord.
Marcus's decision — on professional advice — was to leave the four personal properties where they were and build all future acquisitions through the company. This is the right call for most landlords with meaningful equity and CGT exposure. It avoids triggering large tax events while allowing the new structure to compound over time.
Step 4: Build the portfolio methodically inside the company
Once the first company mortgage was in place, Marcus's broker helped him map a forward acquisition strategy. The key variables were:
- Retained profit: Corporation tax in 2026 sits at 25% for companies with profits over £250,000 (19% for small companies with profits under £50,000, with marginal relief between). Marcus's company paid far less tax on retained rental profit than he would have personally — and that retained profit compounded as deposit capital for the next acquisition.
- Portfolio lender access: Once he held four or more mortgaged properties — the typical definition of a portfolio landlord — he needed lenders with specialist portfolio underwriting. Not every lender will touch a four-plus property portfolio; a whole-of-market broker matters here.
- Stress testing: Each new property was modelled at a stressed interest rate before purchase. Yield alone is not the metric — debt serviceability under a 2% rate rise is the real test.
- Mortgage product selection: Five-year fixed terms gave payment certainty and satisfied lender stress tests more easily than two-year fixes at higher stressed rates.
Step 5: Get the operational structure right
A limited company portfolio demands proper administration. Marcus set up a separate accounting package for the company, used a letting agent that invoiced the company directly, and made sure all insurance policies named the company as the insured party. These details matter at remortgage time — lenders and their solicitors scrutinise the paper trail.
What Happened: A Concrete Result Worth Noting
Eighteen months after incorporating, Marcus had added two properties through the company. His personal tax bill for the year in which those properties were held exclusively in the company was £6,200 lower than the accountant's projected figure had they been held personally. The company retained £14,000 in post-corporation-tax profit — usable as deposit capital for the next acquisition — rather than that money being extracted as income and taxed at 40%.
He also refinanced one of the personal-name properties onto a better rate using his broker's portfolio lender relationships, reducing the blended interest cost across all six properties by 0.18%. Over a five-year term, that is material money.
None of this happened because of a clever trick. It happened because the structure was built deliberately, the mortgage applications were packaged correctly for lenders who specialise in this kind of borrower, and the decisions were sequenced in the right order.
The General Lesson: Structure First, Scale Second
Marcus's story contains the blueprint that applies to almost every landlord considering this route. The limited company SPV structure is not a tax dodge — it is a legally recognised, widely used vehicle that aligns with how the UK tax system currently treats property investment businesses. The advantages are real: corporation tax on retained profit, full mortgage interest deductibility within the company, and the ability to build equity inside a separate legal entity.
The disadvantages are also real: higher mortgage rates, personal guarantee requirements, additional administrative overhead, and the SDLT/CGT barrier to transferring existing properties in. Neither side of the ledger should be ignored.
For landlords starting from zero, the case for incorporating before buying the first property is strong. For those with an existing personal-name portfolio, the decision is more nuanced — and almost always requires a combined conversation between an accountant and a specialist mortgage broker before a single company document is filed. The sequencing of the structure determines whether it works. Get the mortgage strategy wrong and the tax efficiency gains evaporate in higher finance costs. Get both right, and the compounding effect of retained profit building into a growing portfolio is one of the most reliable wealth-building mechanisms available to UK investors in 2026.
Key Takeaways
- Section 24 makes limited company SPVs the default structure for higher-rate taxpaying landlords — mortgage interest is fully deductible against rental income within a company, unlike personal ownership.
- Incorporation triggers SDLT and CGT on existing properties — for most landlords with equity, the pragmatic move is to build new acquisitions through the company and leave existing personal-name properties in place.
- Limited company buy-to-let mortgages carry slightly higher rates but access specialist lenders who understand portfolio landlord structures; a whole-of-market broker with portfolio experience is essential.
- Corporation tax on retained profit (19–25% depending on company size) is significantly lower than personal income tax at 40–45%, allowing profits to compound inside the company as deposit capital.
- Get the operational administration right from day one — separate bank accounts, correctly named insurance policies, and clean accounting all matter at remortgage and refinance time.
Working with Agnes Mortgage
Agnes Mortgage is a whole-of-market UK mortgage broker specialising in complex buy-to-let and portfolio landlord finance, including limited company SPV structures across 100+ lenders. If you're building or restructuring a property portfolio and want to map the mortgage strategy before you make the next move, book a private consultation — your named broker will work through the numbers with you directly.
Frequently asked questions
Is it better to buy property in a limited company or personal name in the UK?
For higher-rate taxpayers, a limited company SPV is usually more tax-efficient because mortgage interest remains fully deductible and retained profits are taxed at corporation tax rates (19–25%) rather than personal income tax rates of 40–45%. However, limited company buy-to-let mortgages carry slightly higher interest rates, so the right answer depends on your tax position, the size of your portfolio, and your long-term hold strategy — ideally assessed with both an accountant and a specialist broker.
Can I transfer my existing properties into a limited company?
Yes, but doing so triggers Stamp Duty Land Tax on market value and potentially Capital Gains Tax on any gains since purchase — making it expensive for most landlords with equity. Incorporation relief under Section 162 TCGA 1992 can defer CGT in some cases, but HMRC's qualifying criteria are strict. Most landlords with existing portfolios are better advised to retain personal-name properties and acquire future investments through the company.
What is an SPV limited company for property investment?
An SPV (Special Purpose Vehicle) is a limited company incorporated specifically to hold and manage property investments, typically registered with SIC code 68100 or 68209. It is a separate legal entity from its directors, meaning rental income, mortgage debt, and tax liability all sit within the company rather than personally. Most specialist buy-to-let lenders in 2026 have dedicated mortgage products for SPV structures.
Do limited company buy-to-let mortgages have higher rates?
Yes — limited company buy-to-let mortgage rates are typically 0.2–0.5% higher than equivalent personal-name products, and arrangement fees can also be slightly higher. However, for higher-rate taxpayers the tax saving on retained profits and full mortgage interest deductibility generally outweighs the additional finance cost over a five-year hold period. A specialist broker can model both scenarios with your specific numbers.
How many properties do I need before I'm classed as a portfolio landlord?
Most lenders define a portfolio landlord as someone with four or more mortgaged buy-to-let properties, including the one being applied for. Portfolio landlords are assessed under specialist underwriting criteria — lenders review the entire portfolio's rental income, debt exposure, and stress-tested serviceability rather than looking at each property in isolation. This makes lender selection and application packaging significantly more complex.