The short answer to "do I pay stamp duty twice when I incorporate my buy-to-let portfolio?" is yes, almost always. Transferring residential property from an individual to a wholly-owned limited company is a chargeable SDLT event under Finance Act 2003 section 53, calculated at the property's market value, with the 5% additional-dwellings surcharge that has applied since 31 October 2024. The only mainstream route to mitigate that bill to nil is genuine partnership incorporation under FA 2003 Schedule 15 paragraph 10. Multiple Dwellings Relief (MDR), recommended by older guides, was abolished on 1 June 2024 and is no longer available.
This guide walks through the rules, the partnership route, the worked SDLT on typical portfolios, and how the SDLT cost sits alongside the CGT and refinancing costs in a complete incorporation cost-benefit. It is the applied SDLT companion to our BTL limited company complete guide.
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The Default Rule: Market-Value SDLT on Connected-Party Transfer
FA 2003 s.53 deems the chargeable consideration on a land transaction to be not less than the market value of the property where the buyer is a company that is connected to the seller. For a sole landlord transferring into their own NewCo, this means the SDLT is calculated on what the property would sell for on the open market today, not on the original purchase price and not on any artificially low nominal price written into the transfer.
The 5% additional-dwellings surcharge applies because the company is acquiring a dwelling and is "treated as having no main residence" by default (FA 2003 Sch 4ZA paras 4-6). The full SDLT rate schedule that applies is the one in our SDLT additional-dwellings table:
| Band | Standard rate | Additional-dwellings surcharge | Total on additional dwelling |
|---|---|---|---|
| £0 - £125,000 | 0% | 5% | 5% |
| £125,001 - £250,000 | 2% | 5% | 7% |
| £250,001 - £925,000 | 5% | 5% | 10% |
| £925,001 - £1,500,000 | 10% | 5% | 15% |
| £1,500,001 and above | 12% | 5% | 17% |
If the property is worth more than £500,000 and the buyer is a "non-natural person" (any company, partnership with a corporate member, or collective investment scheme), the 15% flat rate at FA 2003 Schedule 4A can apply in place of the table above unless ATED relief conditions are met (FA 2003 Sch 4A paras 5-5G). Genuine buy-to-let companies almost always qualify for the relief, but they must claim it on the SDLT return and file an ATED relief declaration annually thereafter.
What Is No Longer Available: Multiple Dwellings Relief
Multiple Dwellings Relief was a hugely popular incorporation tactic from 2011 to mid-2024. It calculated SDLT on the average price per dwelling rather than the total consideration, dramatically lowering the effective rate on a multi-property transfer. Finance (No.2) Act 2024 abolished MDR for any land transaction with an effective date on or after 1 June 2024. Anti-forestalling rules in the same Act block attempted late MDR claims using sub-sale or option arrangements pre-dated to before the cut-off.
Any incorporation completed on or after 1 June 2024 cannot use MDR. Several still-live online articles (including older versions of this page) reference MDR as available. They are out of date. The official confirmation is on the gov.uk MDR guidance page.
The Partnership Route (FA 2003 Sch 15 Para 10)
The one mainstream way to eliminate the SDLT on portfolio incorporation is to transfer the property from a genuine letting partnership into a company in which the partners hold all the shares. FA 2003 Schedule 15 paragraph 10 (read with paragraph 18) calculates the chargeable consideration on a partner-to-connected-company transfer using a formula that, where all the partners own all the company shares in the same proportions as they own the partnership, reduces the chargeable consideration to nil.
What HMRC actually look for
The route is heavily reviewed. HMRC's SDLT Manual (SDLTM34000 onwards) and case law (notably Project Blue Ltd v HMRC [2018] UKSC 30, and HMRC's enquiry practice) require evidence that the portfolio has been run as a partnership in substance, not merely held jointly. Specifically:
- A partnership agreement predating the incorporation by at least the trading period claimed (HMRC's typical comfort window is two years or more).
- SA800 partnership tax returns filed for each year in that window, with the rental income reported through the partnership and apportioned to partners on the partnership-share basis (not on the underlying beneficial ownership of each property).
- Partnership bank account and accounts, separate from any individual landlord account.
- Joint borrowing where possible, in the partnership name or jointly liable. Individual mortgages in one spouse's name only are a strong negative indicator.
- Operational evidence of partnership conduct: managing agents addressed to the partnership, tenancy agreements between the partnership and the tenant, insurance in the partnership name, lender correspondence to the partnership.
Where these are missing (the most common reality for husband-and-wife portfolios that have always filed individual SA105 returns), the partnership route is not available and full market-value SDLT applies. Restructuring the holding into a real partnership before incorporation is possible but takes years, not weeks, and itself triggers transfer SDLT in many cases unless carefully sequenced.
Worked Example: £1m Six-Flat Portfolio
Sophia owns six flats in Manchester through a properly constituted general partnership with her brother Daniel. Each flat is worth £166,667 on the date of incorporation. The partnership has been filing SA800 returns since 2022. They incorporate Smith Property Holdings Limited in May 2026, taking 50/50 shares.
Route A: Without partnership treatment (e.g. if the documentation does not stand up)
| Per flat | £166,667 |
|---|---|
| £0 - £125,000 at 5% | £6,250 |
| £125,000 - £166,667 at 7% | £2,917 |
| SDLT per flat | £9,167 |
| Six flats total | £55,002 |
Route B: With partnership treatment under Sch 15 para 10
Sophia and Daniel each receive 50% of the company shares, matching their partnership share. The chargeable consideration on each flat is reduced to nil under the connected-party formula at Sch 15 para 10(2)-(4). Total SDLT: £0.
The gap (£55,000) is the value of the partnership documentation. If the documentation does not stand up under enquiry, HMRC will reassess to Route A plus interest and a tax-geared penalty (typically 30%-70% of the SDLT depending on disclosure behaviour).
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Worked Example: £600,000 Two-Flat Husband-and-Wife Portfolio
Mark and Helen own two London buy-to-lets jointly. Each flat is worth £300,000. They have always filed individual SA105 returns showing 50/50 of the rents. There is no partnership agreement, no SA800, and no partnership bank account. They are not a partnership. The partnership route is not available.
| Per flat | £300,000 |
|---|---|
| £0 - £125,000 at 5% | £6,250 |
| £125,000 - £250,000 at 7% | £8,750 |
| £250,000 - £300,000 at 10% | £5,000 |
| SDLT per flat | £20,000 |
| Two flats total | £40,000 |
For Mark and Helen, the incorporation arithmetic must therefore recover the £40,000 SDLT from the future tax saving. At a typical higher-rate-vs-corporation-tax saving of around £6,000-£8,000 a year on this size portfolio, payback runs five to seven years. If their intended hold is at least seven years and they want to grow the portfolio further, incorporation can still make sense; if they intend to wind down within five years, it usually does not.
SDLT, CGT s.162 Incorporation Relief, and the Combined Cost
SDLT and CGT have separate reliefs. The one does not affect the other.
CGT side
The transfer of property from an individual to a wholly-owned company is a deemed disposal at market value for CGT (TCGA 1992 s.17). Section 162 incorporation relief defers the gain by rolling it into the base cost of the shares received, provided the entire business (not selected assets) is transferred and the consideration is wholly or partly shares. The relief is automatic but must be claimed correctly and the conditions in s.162(1)-(4) must be met. The HMRC reference is CG65700+ of the Capital Gains Manual.
SDLT side
None of the s.162 conditions affect SDLT. You can claim s.162 incorporation relief for CGT and still pay full market-value SDLT. The two reliefs are independent: only the partnership route under FA 2003 Sch 15 para 10 eliminates SDLT.
Combined cost worked through
For Mark and Helen above (the husband-and-wife two-flat portfolio):
- SDLT: £40,000 (no partnership route, full market-value)
- CGT: deferred under s.162 (assume £180,000 of latent gain rolled into share base cost)
- Refinancing: ~£15,000 (early repayment + new product fees on roughly £450k of borrowing)
- Legal and accountancy: ~£3,500
- One-off incorporation cost: £58,500
The annual recurring saving from moving rental profit out of 40% personal income tax into 19%/25% corporation tax (less the eventual dividend tax on extraction) needs to be modelled against that one-off £58,500 figure across the intended hold period.
The Filing and Land Registry Steps
- SDLT5 within 14 days. The SDLT return must be filed within 14 calendar days of the effective date (normally completion). Late filing penalties start at £100, rise to £200 after three months, and turn tax-geared at twelve months.
- Land Registry transfer. HM Land Registry will not register the transfer of the legal title to the company without sight of the SDLT5 certificate from HMRC. Application is typically AP1 with TR1.
- Lender consent. If the existing mortgage is being redeemed and a new company mortgage put in place, both must be coordinated with the SDLT return and Land Registry transfer to avoid gaps in title or breaches of mortgage conditions.
- ATED relief declaration (if needed). Where any single property is worth more than £500,000 at the date of acquisition, file an ATED relief declaration return by 30 April following acquisition.
- Corporation tax registration. The new company must be registered for corporation tax within three months of starting to trade (i.e. starting to receive rental income).
When Incorporation Is and Is Not Worth the SDLT
The SDLT cost is the single largest one-off item in any incorporation cost-benefit. The decision turns on three numbers:
- Total SDLT exposure (partnership route or not).
- Annual recurring tax saving from moving rental profit into the corporation tax regime, net of dividend tax on extraction (or zero if profits are retained).
- Intended hold period: how long the portfolio will sit inside the company before any disposal or wind-up event.
The breakeven SDLT cost / annual saving multiple is typically 4-7 years. Anything shorter than 4 years rarely justifies the SDLT cost alone. Anything longer than 8 years almost always does. The qualitative factors (mortgage availability through limited-company BTL products, inheritance planning via different share classes, asset protection through limited liability) sit on top of that arithmetic.