Integral Features & Capital Allowances on Commercial Property: A Trade's Guide (2026)

What "Integral Features" Actually Means

"Integral features" is a defined category in the Capital Allowances Act 2001. It exists because, historically, HMRC and taxpayers argued endlessly about whether things like wiring and pipework were part of the building (no relief) or plant (relief). The integral features rules settled the question by listing specific systems that always qualify for capital allowances, regardless of how fixed to the building they are.

The statutory list of integral features is:

• Electrical systems, including general lighting
• Cold water systems
• Space or water heating systems, and powered ventilation systems
• Air conditioning and air cooling systems
• Lifts, escalators and moving walkways
• External solar shading

If your new unit has been rewired, has central heating, has a hot and cold water supply to a kitchen or washroom, or has air conditioning in the office, all of that expenditure sits in the integral features category. For a typical commercial fit-out this can be a substantial slice of the total bill.

The Special Rate Pool — and Why You Rarely Wait for It

Integral features go into what is called the "special rate pool". On their own, assets in this pool attract a writing-down allowance (WDA) of just 6% per year on a reducing-balance basis. That is painfully slow — it takes well over a decade to relieve most of the cost, and you never fully clear the pool because each year's allowance is a percentage of the diminishing balance.

The good news is that you almost never have to settle for 6%. There are faster routes:

• Annual Investment Allowance (AIA): Available to sole traders, partnerships and companies. It gives 100% relief in the year of spend on qualifying plant and machinery, including integral features, up to a limit of £1 million per year. Most trade businesses fitting out a single unit will fall comfortably within this limit and can therefore write off integral features in full immediately.
• Full expensing: Available to companies paying Corporation Tax. For new and unused main-rate plant there is 100% relief, and for new special-rate assets (integral features) there is a 50% first-year allowance in year one, with the remaining 50% entering the special rate pool at 6%. Full expensing has no annual cap, so it matters for larger spends above the AIA limit.

In practice, the planning order is simple: use AIA first to soak up qualifying spend at 100%, and fall back on first-year allowances or pool WDAs for anything above the cap. For most trades buying or fitting one set of premises, AIA alone clears the lot.

Plant & Machinery Fixtures — the Main Pool at 18%

Not everything embedded in a commercial building is an integral feature. A broader category of "plant and machinery" fixtures attracts main pool treatment, with a writing-down allowance of 18% per year — and, again, AIA can normally accelerate this to 100% in year one.

Typical main pool fixtures in a trade unit or office include:

• Sanitaryware — toilets, basins, washroom fittings
• Fitted kitchens and kitchenettes (the units and worktops, not the building they sit in)
• Security and alarm systems, CCTV and access control
• Fire alarm systems
• Signage and demountable partitioning
• Trade-specific machinery and equipment installed in the premises

The distinction between integral features (special rate, 6%) and main pool fixtures (18%) only really bites once you are over the AIA limit. Below it, both go in at 100% — but the classification still needs to be right for your records and for any future sale.

Buying a Second-Hand Building: Where the Real Money Is

The biggest opportunity — and the one most often missed — is buying an existing commercial building. When you purchase a second-hand property, a meaningful percentage of the price you pay represents embedded fixtures: the wiring, heating, water systems, air conditioning, sanitaryware and so on that came with the building. A proper capital allowances survey apportions the purchase price and identifies those embedded fixtures as qualifying expenditure.

Depending on the building type, qualifying fixtures can represent anywhere from a low single-digit percentage up to 25% or more of the purchase price. On a £500,000 unit, that can mean tens of thousands of pounds of relief that would otherwise be left on the table — and which most buyers never even look for.

But there are two procedural hurdles you must clear on a second-hand purchase:

• The s198 election: When fixtures change hands, buyer and seller normally agree a value for them in a written election under section 198 CAA 2001, signed within two years of the transaction. This fixes the figure both sides use — the seller's disposal value and your acquisition value. Get this addressed at the contract stage; chasing a seller after completion is much harder.
• The pooling requirement: Since 2014, you can generally only claim fixtures if the past owner who was entitled to allowances had "pooled" the relevant expenditure (brought it into a capital allowances pool). If a previous owner never claimed, the entitlement can be lost for good. This is why due diligence on the building's allowances history is essential before you exchange.

The practical message: raise capital allowances during the conveyancing process, not after. A specialist survey and the right contract clauses protect a relief that is often worth more than your solicitor's entire fee.

The Slow Lane: Structures and Buildings Allowance

What about the actual fabric — the walls, roof, floor slab, foundations and structure? That does not qualify as plant. Instead it may attract the Structures and Buildings Allowance (SBA), which gives a flat 3% per year on a straight-line basis on the cost of construction or renovation of commercial buildings, claimed over roughly 33 years.

The SBA is far less valuable than plant and machinery relief: 3% straight-line versus 100% via AIA. It also cannot be claimed on the land itself, only on construction cost, and there are detailed rules about allowance statements and what happens on sale. The takeaway for a trade is simple — the more of your spend that can be correctly classified as integral features or plant rather than structure, the faster you get your relief. That classification work is exactly what a capital allowances survey does.

Quick Reference: Pools and Rates (2026)

Worked Example: Fitting Out a Trade Unit

Imagine a limited company groundworks firm buys and fits out a 250m² industrial unit. The numbers below are illustrative 2026 figures to show how the apportionment and relief work — your own survey will produce a precise breakdown.

• Second-hand building purchase: £420,000 (of which land is £120,000, structure £240,000, embedded fixtures £60,000 after a survey and s198 election)
• New office fit-out — rewire and lighting: £28,000 (integral features)
• New gas warm-air heating and ventilation: £16,000 (integral features)
• Hot and cold water plus a new washroom: £9,000 (integral features and sanitaryware)
• Intruder alarm, CCTV and fire alarm: £7,000 (main pool fixtures)
• Fitted kitchen, signage and partitioning: £6,000 (main pool fixtures)

Qualifying plant and machinery (integral features plus main pool fixtures) totals roughly: £60,000 embedded fixtures + £28,000 + £16,000 + £9,000 + £7,000 + £6,000 = £126,000. That is comfortably within the £1 million AIA limit, so the company can claim 100% of the £126,000 in year one.

At a 25% Corporation Tax rate, £126,000 of immediate relief is worth about £31,500 off the company's tax bill in the first year. The £240,000 structure cost goes to the SBA at 3% — around £7,200 a year — and the £120,000 land attracts no allowances at all. Without a capital allowances survey, that £60,000 of embedded fixtures inside the purchase price would almost certainly have gone unclaimed, costing the company around £15,000 in lost relief on the purchase alone.

AIA Timing — Get the Year Right

AIA is a per-period allowance, so timing matters. The £1 million limit applies to your accounting period; if your period straddles a date when the limit changes, the cap is apportioned and special transitional rules can apply. Bringing a big spend forward or back across a year-end can change whether it all gets 100% relief.

Relief is given when the expenditure is "incurred", broadly when there is an unconditional obligation to pay — usually the date of the invoice or the contract milestone, not necessarily when cash leaves the bank. If you are planning a large fit-out near your year-end, talk to your accountant about the optimal timing before you commit to invoices.

Record Keeping and Getting a Survey

Capital allowances claims live or die on documentation. To protect your claim you should keep:

• Itemised invoices for the fit-out, broken down by trade and element rather than a single lump sum
• The capital allowances survey report apportioning a property purchase
• The signed s198 election and any correspondence with the seller about pooling
• The purchase contract and completion statement showing the price split between land, structure and fixtures
• An SBA allowance statement for any qualifying construction or renovation

For anything beyond a modest fit-out — and certainly for a building purchase — a specialist capital allowances surveyor usually pays for themselves many times over. They combine surveying and tax knowledge to identify and value qualifying items your general accountant may not break out, and they prepare the report HMRC expects to see. Ask your accountant for a referral, and raise it early so it can be built into the deal.

Frequently Asked Questions

Can a sole trader claim integral features, or is it just companies?

Both can claim. The Annual Investment Allowance and writing-down allowances are available to sole traders, partnerships and companies alike. Full expensing and the 50% first-year allowance on special-rate assets, however, are only available to companies paying Corporation Tax.

Do I get capital allowances if I rent my unit rather than buy it?

Often yes — if you pay for the fit-out yourself. Expenditure you incur on integral features, fixtures and plant in leased premises can still qualify, even though you do not own the building. The landlord's own spend is a separate matter. Keep your fit-out invoices in your own business name.

What is the difference between integral features and the main pool?

Both are plant and machinery, but integral features sit in the special rate pool at 6% and main pool fixtures sit in the main pool at 18%. The classification only affects your relief once you exceed the £1 million AIA limit — below that, AIA gives 100% on either.

Why is the s198 election so important?

Without an agreed s198 election and a satisfied pooling requirement, you may be unable to claim allowances on fixtures embedded in a second-hand building you buy — potentially losing relief worth a real percentage of the purchase price. It has to be dealt with as part of the transaction, not after.

Is the Structures and Buildings Allowance worth claiming?

Yes — 3% a year on construction cost is still relief you would otherwise miss. It is just far slower than plant and machinery relief, which is why the priority is to correctly classify as much spend as possible as integral features or fixtures first, then put the structural balance through the SBA.