Tax Planning for Landlords with Multiple Properties in London: The 2026 MTD Survival Guide 

If you own more than one rental property in London, 2026 brings important tax changes. HMRC has introduced Making Tax Digital for many landlords. Additional property purchases now attract a 5% SDLT surcharge. The proposed High Value Council Tax Surcharge could also affect some London properties from 2028. Understanding these changes now can help you avoid costly mistakes.

Most online tax guidance focuses on landlords with one buy-to-let property. Portfolio landlords face a different set of challenges. Mortgage interest restrictions affect several properties at once. Capital gains can arise at different times, and each property now requires digital records under MTD from April 2026.

This guide breaks down what’s changed, what it means for multi-property landlords, and the planning moves worth making before your next filing deadline. It’s the kind of portfolio-level tax advice and accounting services a specialist Property Tax Accountant London landlord builds a filing calendar around. 

2026 HMRC Rules for London Landlords: What’s Confirmed and What’s Still Proposed 

Before any planning conversation, it helps to know what’s changed and what’s still proposed: 

• Making Tax Digital for Income Tax (MTD ITSA) became mandatory on 6 April 2026 for landlords with combined gross income over £50,000. It’s based on gross rental income across all properties, not profit, so it captures a large share of London portfolio landlords almost by default. The threshold drops to £30,000 from April 2027 and £20,000 from April 2028. This is a confirmed, legislated policy. 

• Quarterly digital submissions now replace the single annual Self-Assessment return for those in scope, with an End of Period Statement and Final Declaration by 31 January. HMRC has confirmed a penalty-free grace period for the first 12 months, but record-keeping starts immediately. 

• SDLT on additional properties carries a 5% surcharge on top of standard rates, applied to the whole purchase price once the property is worth £40,000 or more. Combined with the nil-rate threshold reverting to £125,000, buying your next property now costs meaningfully more upfront than it did two years ago. This is also confirmed, in-effect policy. 

• The High Value Council Tax Surcharge, widely reported as a “mansion tax,” was announced in the Autumn 2025 Budget and is proposed to take effect from April 2028 for property valued at £2 million or more, based on 2026 valuations, with charges ranging from £2,500 to £7,500 a year, rising with CPI. This measure is still under government consultation, which closed 14 July 2026, and the final thresholds, bands, and exemptions have not yet been legislated. Treat these figures as the current proposal, not confirmed by law. It’s still a real consideration for landlords holding higher-value stock in boroughs like Kensington and Chelsea, Westminster, or Camden. 

• Section 24 continues to restrict mortgage interest relief to a 20% tax credit rather than a full deduction. This is a confirmed, long-standing rule that hits leveraged, multi-property landlords disproportionately, because the effect multiplies across every mortgaged unit. 

• Property income tax rates rise by 2 percentage points from April 2027, confirmed in the same Autumn 2025 Budget as the mansion tax. Basic, higher, and additional rates on rental income move to 22%, 42%, and 47%. Landlords holding property through a limited company are unaffected, which makes this one of the clearer near-term reasons to revisit ownership structure across a portfolio before the change lands. 

None of these changes exist in isolation. For a landlord with one property, each is a manageable adjustment. For a landlord with five or ten, they interact, and that’s where the real planning opportunity, or the real risk, sits. 

Why Multiple Properties Multiply Your Tax Complexity, Not Just Your Income 

A single-property landlord deals with one set of expenses, one mortgage, one CGT calculation if they ever sell. A portfolio landlord manages several rental properties at the same time. HMRC combines income from every property when calculating tax obligations. This creates both risks and planning opportunities. 

The trap: gross rental income is added together across every property to determine your MTD threshold and your income tax band. A portfolio that looks like modest property-by-property can push you into higher-rate tax and mandatory digital reporting far sooner than expected. 

The opportunity: because everything is aggregated, losses on one property can offset profits on another, and disposals, refinancing, or capital expenditure can be sequenced to smooth your tax position year to year rather than reacting to property by property. 

This is exactly the kind of cross-portfolio planning a specialist Property Tax Accountant in London works through with clients, treating the portfolio as one system rather than a collection of separate assets. 

Making Tax Digital: What Portfolio Landlords Need to Do Now 

If your combined gross rental income across all properties exceeds £50,000, you’re in scope for MTD ITSA from the 2026/27 tax year, with your first quarterly update due 7 August 2026 if your obligation started at the beginning of the tax year. 

Practically, that means: 

1. Digital records for every property, not a single spreadsheet with informal notes. HMRC-recognised software needs income and expenses broken down to generate quarterly submissions. 

2. Four quarterly updates plus a Final Declaration, replacing the once-a-year rhythm most landlords are used to. Missing a deadline outside the grace period starts accumulating penalty points. 

3. A decision on software and process now. Reconstructing a year of scattered property records under quarterly deadline pressure is far harder than setting up clean digital habits in advance. 

This is also the moment to review whether repairs versus improvements are categorised correctly, since quarterly reporting leaves far less room to tidy up expense treatment retrospectively. If your records span several properties, a Property Tax Specialist London landlords use can set this up correctly once rather than fixing it under deadline pressure. See our Property Tax Specialist London service for how this is structured. 

Ownership Structure: Personal Name, Company, or Mixed Portfolio? 

For landlords adding to a portfolio, the incorporation question comes up constantly, and there’s no single right answer. A limited company can offer full mortgage interest deductibility and a lower corporation tax rate on retained profits, which is attractive for landlords reinvesting rather than drawing income. But transferring existing properties into a company can trigger both SDLT (at the higher surcharge rates) and Capital Gains Tax, and HMRC will scrutinise whether your letting activity qualifies as a genuine business before allowing incorporation relief. 

For a multi-property portfolio, this decision is rarely all-or-nothing. Some landlords hold newer acquisitions through a company while retaining older, lower-mortgage properties personally, where the Section 24 impact is smaller. With property income tax rates rising to 22%, 42%, and 47% from April 2027 for personally held portfolios, and limited company landlords unaffected by that rise, the incorporation question is worth revisiting even if you decided against it previously. The right mix depends on leverage, income needs, and exit plans, which is why it deserves proper modelling rather than a generic rule of thumb. Our Property Tax Specialist London team runs this comparison property-by-property, since mixed structures are often the most tax-efficient outcome. 

Capital Gains Tax: Timing Disposals Across a Portfolio 

Selling one property from a multi-property portfolio rarely happens in isolation. Losses banked on an earlier sale, the timing of a disposal relative to your tax year, and whether a sale pushes other portfolio income into a higher band, all affect your final CGT bill. 

For London landlords specifically, values in several boroughs have moved unevenly over the past two years, so some properties may show gains while others sit near break-even. Sequencing which property, you sell, and when, can materially change your total tax exposure rather than treating each sale as a standalone event. We cover disposal timing in more depth on our Property Taxes blog. 

Stamp Duty Planning When Growing the Portfolio 

Every additional property purchase carries the 5% SDLT surcharge from the first pound above £40,000, on top of the standard rate, a cost that compounds as a portfolio grows. Before your next purchase, model the full acquisition cost, not just the headline price, since the surcharge affects your effective loan-to-value and can shift a deal from comfortably affordable to marginal once tax, deposit, and financing costs are combined. 

The 2028 Mansion Tax: Plan Now, Not in 2027 

Even though the High Value Council Tax Surcharge is proposed for April 2028 and not yet finalised, the valuations underpinning it are based on 2026 market values, making this year the relevant planning window regardless of how the consultation concludes. If your portfolio includes property likely to sit above £2 million, get an independent valuation now, understand which band you’d likely fall into, and factor the potential annual surcharge into your long-term holding versus selling decisions ahead of the 2028 date. We’ll confirm the final rules once legislation is settled. 

A Practical Checklist for 2026 

Whether you handle this yourself or bring in Property Tax Advisors and Accountants, here’s where to start: 

• Confirm whether your combined gross rental income puts you in scope for MTD ITSA this year or next 

• Move to HMRC-recognised digital record-keeping across every property, not just your largest one 

• Get a professional review of your ownership structure before your next acquisition or refinance 

• Model the full cost of your next purchase including the 5% SDLT surcharge 

• Get any property near the £2 million mark independently valued ahead of the 2028 surcharge 

• Review Section 24’s impact across your full mortgage book, not property by property 

• Model how the 2027 property income tax rate rise affects personally held properties versus a company structure 

Why Work with a Specialist Property Tax Accountant in London 

Generic accounting advice struggles to keep pace with how fast landlord-specific rules are moving, and portfolio landlords have the most to lose from a one-size-fits-all approach. Working with dedicated Property Tax Advisors and Accountants who track HMRC’s landlord-specific changes as they happen means your MTD setup, ownership structure, and disposal timing are planned together, not fixed in isolation after the tax has already been triggered. 

If you’re searching for property tax advisors near you who actually specialise in multi-property portfolios rather than general practice accounting, our team works exclusively with London landlords and investors on exactly these issues. Browse more insights on our Property Taxes blog, or get in touch for tax advice and accounting services built around your portfolio. 

Speak to a Property Tax Accountant London landlords trust. Visit www.bsassociate.co.uk or call 0207 183 5956 to book a portfolio review before your next MTD deadline. 

Frequently Asked Questions