NOT financial advice - seek advice from a professional for your specific situation

    TaxKilnUK tax guidance
    TaxKilnUK tax guidance

    Structures and Buildings Allowance (SBA)

    Structures and Buildings Allowance (SBA) gives **3% per annum STRAIGHT-LINE** capital allowances on qualifying NON-RESIDENTIAL CONSTRUCTION + RENOVATION expenditure. 33⅓-year allowance period (matches the 3% straight-line). Introduced 29 October 2018 at 2% p.a.; increased to 3% from 1 April 2020 / 6 April 2020. Fills the historical gap where commercial BUILDINGS fell entirely outside the plant + machinery capital allowances regime. **Qualifying expenditure**: construction costs for new non-residential structures + buildings; capital renovation / conversion of existing commercial structures; written contract on or after 29 October 2018. **Qualifying activities**: trades, professions, UK/overseas property businesses (excluding residential + previously FHL, abolished April 2025 so technically FHL now in ordinary property business but typically residential = non-qualifying anyway), managing company investments, mining + quarrying. **What does NOT qualify**: residential buildings; expenditure already qualifying for plant + machinery allowances; land. **WRITTEN ALLOWANCE STATEMENT REQUIRED**: address, earliest contract date, total costs, first non-residential use date. Buying a used building: statement must be obtained from previous owner. **NO BALANCING ADJUSTMENTS on disposal**: purchaser steps into seller's remaining allowance period.

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    What this relief is, in plain English

    SBA is the UK's newest capital allowance regime, introduced in 2018 to fill the long-standing gap where commercial BUILDINGS got NO capital allowances (plant + machinery allowances had always existed for movable equipment; structures themselves had no relief). The 3% straight-line rate gives modest annual relief but cumulative meaningful value over the 33⅓-year allowance period. Mechanic is simple in principle. Qualifying expenditure (construction + renovation costs on non-residential buildings) gets 3% per year deduction over 33⅓ years. No reducing-balance; no balancing adjustments on disposal; no pool mechanics. Purchaser of a used building steps into the seller's remaining allowance period, preserving the cost basis + period across ownership changes. Key complexity: the WRITTEN ALLOWANCE STATEMENT requirement. Sellers of commercial buildings must provide the statement to enable the buyer's continuing SBA claim. Buyers should demand the allowance statement during conveyancing, without it, SBA is permanently lost on that property. Builders + developers acquiring multiple commercial properties build allowance-statement documentation discipline into their property acquisition processes. Qualifying activities are broad: trades, professions, UK + overseas property businesses (excluding residential), managing company investments, mining + quarrying. The exclusion of residential is fundamental, SBA is specifically a commercial-property relief, complementing the residential-property reliefs (Replacement of Domestic Items + Section 24 mechanics).

    How it works

    3% straight-line over 33⅓ years

    Qualifying expenditure × 3% per year = annual deduction. Continues for 33⅓ years until 100% relieved. Straight-line (not reducing balance). No pool mechanics, separately tracked per building. Standard rate has been 3% since 1 April 2020 / 6 April 2020 (was 2% from 29 October 2018 introduction).

    Qualifying construction + renovation costs

    Construction costs for new non-residential structures + buildings; capital renovation + conversion of existing commercial structures. Must be subject to written contract on or after 29 October 2018. EXCLUDED: expenditure qualifying for plant + machinery allowances (no double-claiming); land cost; residential buildings + structures within grounds of residence.

    Qualifying activities + non-residential test

    Trades, professions, UK + overseas property businesses (excluding residential), managing company investments, mining + quarrying. The NON-RESIDENTIAL test is fundamental, residential buildings excluded entirely. From April 2025 FHL abolition: former FHLs typically residential properties, so SBA still wouldn't apply in most cases.

    Written allowance statement mandatory

    Must record: address/description; earliest written construction contract date; total qualifying costs; first non-residential use date. Required to support any SBA claim. On purchase of USED commercial building: obtain allowance statement from previous owner, without it, SBA permanently lost. No balancing adjustments on disposal, purchaser steps into seller's remaining allowance period.

    Who qualifies

    Interactions with other reliefs

    AIA + Full Expensing + WDA

    P&M allowances are EXCLUDED from SBA (no double-claiming). On a new commercial building: structural shell + non-mechanical fitments = SBA. Integral features (electrical, lighting, heating, hot/cold water) = special rate pool 6%. Loose plant + IT + furniture = AIA / Full Expensing / main pool. Specialist cost segregation analysis allocates total project cost across the multiple relief categories.

    Land Remediation Relief (LRR)

    LRR (150% deduction on qualifying remediation expenditure, Ltd Co only) can apply to contaminated commercial sites; SBA applies to the subsequent commercial-building construction on remediated land. Two separate reliefs on different cost types within the same project.

    Section 24 Mortgage Interest Restriction

    Section 24 applies to INDIVIDUAL residential landlords' mortgage interest. SBA applies to COMMERCIAL property structures. Mostly non-overlapping, though some mixed-use scenarios (commercial property with residential element, or residential property converted to commercial) may need careful apportionment between regimes.

    Common mistakes + audit triggers

    Worked example

    Felicity, Manchester - Ltd Co director investing in new office building for trading subsidiary (2025/26)

    Felicity's Ltd Co commissions a new £800,000 office building in Manchester for use by her trading subsidiary. Construction contract signed January 2025; completion + first non-residential use June 2025. Project cost breakdown: £600,000 building shell + structure (SBA-eligible); £150,000 integral features (special rate pool 6%); £50,000 loose plant + IT + furniture (AIA-eligible).

    Calculation: **Step 1: SBA on £600,000 building shell.** 3% × £600,000 = **£18,000/year for 33⅓ years**. Total lifetime SBA relief: £600,000 (100% over allowance period). **Step 2: Special rate pool on £150,000 integral features.** 50% FYA portion (since Ltd Co + new + qualifying): £75,000 immediate deduction. Residual £75,000 in special rate pool at 6% reducing balance going forward. **Step 3: AIA on £50,000 loose plant + IT + furniture.** 100% AIA: £50,000 immediate deduction. **Year 1 total capital allowances:** Special rate pool WDA: 6% × £75,000 = £4,500. Total year-1 allowances: £18,000 (SBA) + £75,000 (50% FYA on integral features) + £4,500 (special rate pool WDA) + £50,000 (AIA) = **£147,500**. CT saving at 25%: £147,500 × 25% = **£36,875** in year 1. **Year 2-33⅓ ongoing:** SBA continues at £18,000/year for 33⅓ years. Special rate pool reduces 6% per year on residual. AIA-claimed items: no further allowances (fully relieved). Lifetime SBA + special rate pool total relief: £600,000 + £150,000 = £750,000. Cumulative CT saving at 25%: ~£187,500 over the building's allowance lifecycle. **Allowance statement preparation:** 1. Document property address + freehold details. 2. Record earliest written construction contract date (January 2025). 3. Total qualifying SBA cost £600,000 (with detailed cost breakdown supporting allocation between SBA vs P&M). 4. Date of first non-residential use (June 2025). 5. Statement retained for the duration of company ownership; provided to any future purchaser to enable their continuing SBA claim. **Disposal mechanic (if Felicity sells the building in 2030 with 28+ years SBA remaining):** Buyer receives allowance statement → steps into remaining SBA period → continues 3% on £600,000 original cost for the remaining ~28 years. No balancing charge for Felicity's company on the SBA portion. Special rate pool disposal: standard mechanic (proceeds reduce pool; balancing charge if proceeds exceed pool balance).

    Statute reference: Capital Allowances Act 2001 + Finance Act 2019 ss.270AA-270IJ. HMRC manual: CA90000 onwards.

    Frequently asked questions

    What happens if I miss the Self Assessment deadline?+
    The Self Assessment deadline is 31 January (online filing) for the previous tax year. Miss it and HMRC apply an automatic £100 penalty. Beyond that: £10 per day from 3 months late (capped at £900), 5% of tax due at 6 months late, and another 5% at 12 months late, under Schedule 55 of the Taxes Management Act 1970. If you have a genuine reason (serious illness, bereavement, technical issue with HMRC's systems) you can appeal with evidence; HMRC accepts reasonable excuse appeals in most genuine cases.
    Do I need an accountant or can I file Self Assessment myself?+
    Legally you can file Self Assessment yourself via gov.uk for free, most simple sole-trader returns (single income source, basic expenses) are realistic to self-file. An accountant adds real value when: your trading profit is above £40,000 (extraction-strategy decisions matter), you have multiple income streams (PAYE + self-employment + property + dividends), you've crossed the £90,000 VAT threshold, you're considering incorporation, or you have an HMRC enquiry. Expect to pay £400-£1,500/year for a typical sole-trader accountant; the cost is itself a deductible expense.
    How do payments on account work?+
    When your Self Assessment tax bill exceeds £1,000 for the first time, HMRC requires payments on account toward NEXT year's tax. Half the current bill is due 31 January (alongside the current bill); the other half is due 31 July. So your first January after crossing the threshold can hit with a double-bill: last year's balance + first payment on account. Adjust via Form SA303 if you expect next year's income to drop substantially. Payments on account don't apply if more than 80% of your tax is collected via PAYE.
    I'm converting a barn into office space, can I claim SBA on the conversion cost?+
    Yes, if the barn was previously non-residential + the converted office is non-residential. SBA covers capital RENOVATION + CONVERSION of existing commercial structures. The 3% allowance applies to the conversion expenditure (architects, builders, structural works, fit-out where capital in nature). Note: any expenditure qualifying for PLANT + MACHINERY allowances (electrical systems, lighting, heating, plumbing) is EXCLUDED from SBA, must claim via AIA / Full Expensing / WDA instead. Allocate conversion costs between SBA (structural/building shell) + P&M allowances (integral services), typically requires specialist surveyor cost segregation. SBA 3% straight-line over 33⅓ years on £200,000 of qualifying barn conversion = £6,000/year for 33 years, modest annual relief but cumulative over the long allowance period.
    Can I claim SBA on a residential property converted to commercial use?+
    Generally yes if the conversion creates a genuinely non-residential property used for qualifying activities. The TIMING of qualifying use matters: SBA only available from the date of FIRST NON-RESIDENTIAL USE. Pre-conversion costs might be claimable; some restrictions apply where the property remains substantially residential in character or has dual use. The 'allowance statement' must record the date of first non-residential use. Common scenario: residential flat above commercial shop converted entirely to commercial → SBA available from date the residential element ceases. Mixed-use properties more complex, apportionment + specialist advice typically needed.
    What's the allowance statement + why does it matter?+
    A WRITTEN ALLOWANCE STATEMENT is a MANDATORY document recording: (1) property address / description; (2) date of EARLIEST written construction contract; (3) TOTAL qualifying costs; (4) DATE OF FIRST USE for a non-residential activity. Required to support any SBA claim. **Buying a USED building**: you must OBTAIN the allowance statement from the PREVIOUS OWNER, without it, you CANNOT make the SBA claim. This creates a significant due diligence requirement on commercial property purchases, request the allowance statement during conveyancing. If the seller can't provide one (lost, never created, dispute), the buyer permanently loses SBA on that property. The mechanic was specifically designed to prevent double-claiming by requiring documentary chain-of-title.
    What happens to SBA on disposal of the building?+
    **NO BALANCING ADJUSTMENTS** on disposal, different from main pool / special rate pool / EV FYA mechanics. The purchaser STEPS INTO the seller's remaining allowance period. Example: building constructed 2020 with £500,000 qualifying SBA costs; seller claimed SBA for 5 years (2020-2025); sells to buyer in 2025 with 28⅓ years of allowance period remaining. Buyer takes over SBA at 3% on the original £500,000 cost basis for the remaining 28⅓ years. Buyer doesn't get a fresh 33⅓-year period; the historic cost basis + allowance period persists across owners. This is unusual + favourable mechanic, most other capital allowance regimes have balancing adjustments triggered by disposal. Reflects the long-life nature of buildings + the cost-tracking complexity if balancing adjustments applied.

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