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The Definitive Guide to
Capital Allowances for Accountants
Go beyond the basics of P&M and learn how to uncover the significant, hidden tax relief locked in your clients' commercial properties.
Why Capital Allowances Are Your Biggest Untapped Opportunity
An estimated £70-96 billion in capital allowances goes unclaimed every year. 87% of businesses fail to claim their full entitlement. This isn't just a compliance task; it's a massive value-add opportunity.
While most accountants confidently claim for loose items like computers and furniture, the real value lies in embedded fixtures within property — the electrical systems, HVAC units, and plumbing hidden within walls, floors, and ceilings. These are where most claims are missed, and where your clients are losing out on significant tax relief.
Your Roadmap to Capital Allowance Mastery
This guide covers the key areas where accountants can add the most value.
Understanding Embedded Capital Allowances
The hidden value in walls, floors, and ceilings — and how to uncover it.
Read the full guide → 02Making Retrospective Claims
How to claim for past expenditure without amending tax returns.
Read the full guide → 03Navigating Section 198 Elections
The critical rules for property transactions and when they don't apply.
Read the full guide → 04Talking to Clients About Tax Savings
How to start the conversation with confidence and add real value.
Read the full guide →The Fundamentals
Capital Allowance Fundamentals for Accountants
What are Capital Allowances?
Capital allowances are the tax equivalent of depreciation. They allow businesses to deduct the cost of qualifying capital expenditure from their taxable profits. Unlike accounting depreciation, which is a matter of accounting policy, capital allowances are a matter of tax law.
What is Plant & Machinery?
To qualify for capital allowances, an item must be "plant" or "machinery". HM Revenue & Customs applies two key tests:
- The Function Test: Does the item perform a function in the business? (e.g., a production machine, computer, or vehicle)
- The Premises Test: Is the item "integral" to the building? (e.g., HVAC systems, lighting, plumbing)
The Pool System
Capital expenditure on plant and machinery is generally pooled together, with allowances given as a percentage of the pool value:
| Allowance | Rate | Limit | Notes |
|---|---|---|---|
| Annual Investment Allowance (AIA) | 100% | £1,000,000/year | Available for most plant & machinery |
| Full Expensing | 100% | None | New main rate pool assets only |
| Writing Down Allowance (WDA) | 18% | N/A | Main rate pool (reducing balance) |
| WDA (Special Rate) | 6% | N/A | Special rate pool (reducing balance) |
| Structures & Buildings Allowance (SBA) | 3% | N/A | New non-residential buildings |
What Are Embedded Capital Allowances?
Embedded capital allowances are the fixtures and fittings that become part of the building itself — the systems and installations that would typically be included in a structural survey rather than a fit-out inventory.
Common Examples of Embedded Allowances
- Heating, Ventilation, and Air Conditioning (HVAC) — Central heating systems, air conditioning units, ventilation ductwork
- Electrical Systems — Wiring, lighting fixtures, distribution boards, fire alarm systems
- Plumbing and Piping — Water pipes, drainage systems, bathroom fixtures
- Lifts and Escalators — Passenger and goods lifts, escalators
- Security Systems — CCTV, access control systems, intruder alarms
- Kitchen Equipment — Commercial kitchen extraction, refrigeration units (in certain contexts)
Why Accountants Miss These
There are three main reasons why embedded allowances are so frequently missed:
- Lack of Surveying Knowledge: Accountants are not trained to identify what is "embedded" in a building. It requires a chartered surveyor's eye.
- Incomplete Invoices: Builder and contractor invoices often bundle everything together without itemising individual fixtures.
- No Visual Access: Many embedded items are hidden behind walls or ceilings, making them invisible without a physical survey.
How to Make a Retrospective Capital Allowance Claim
A common misconception is that capital allowances can only be claimed in the year of expenditure. In reality, as long as the asset is still owned, a claim can be made at any time — even years later.
The Key Principle: Continuous Ownership
Capital allowances are not time-limited to the year of purchase. If a business owns a qualifying asset, they can claim allowances throughout the period of ownership. This applies whether:
- The expenditure occurred in a previous tax year
- The previous owner didn't claim allowances
- The business has only recently become aware of the opportunity
Retrospective Claim vs. Amending a Return
It's important to distinguish between two approaches:
Retrospective Claim
Claim allowances for the current year based on existing capital expenditure. No need to amend prior tax returns. The allowance reduces taxable profits in the current year.
Amending a Return
Go back and amend a previous year's tax return to claim allowances in that year. More complex, subject to time limits (normally 4 years), but may result in a tax repayment.
Time Limits to Consider
While you can make a retrospective claim at any time while the asset is owned, if you want to amend a previous return to claim in that year, you must do so within:
- HMRC Business Tax Window: Normally 4 years from the end of the relevant tax year
- Discovery Assessments: HMRC can also assess beyond this window in certain circumstances
Section 198 Elections Explained
Section 198 of the Capital Allowances Act 2001 governs how capital allowances are allocated between the buyer and seller in property transactions. Understanding this provision is essential for advising clients buying or selling commercial property.
What Does Section 198 Do?
When a property is sold, the seller and buyer can make an election (within 2 years of the sale) to:
- Transfer some or all of the unclaimed capital allowances to the buyer
- Alternatively, allocate a specific amount to the seller
This election is binding on both parties and cannot be varied after the deadline.
The Critical Clarification: What It Does NOT Apply To
This is where many accountants go wrong. A Section 198 election is ONLY relevant to:
- Property purchases where the seller had unclaimed allowances
It does NOT apply to:
- Leasehold improvements — where the tenant has funded improvements to a rented property
- Renovation or conversion costs — where the property owner has renovated an existing building
- New builds — where the property was constructed by the owner
In these scenarios, there is no "seller" to make an election with. The allowances belong entirely to the person who incurred the expenditure.
How to Talk to Clients About Tax Savings
Many accountants avoid raising capital allowances with clients because they fear looking ignorant or embarrassing themselves. But the conversation doesn't have to be complicated — especially when you have the right tool.
The Fear of Embarrassment
Accountants are trained to be precise. Bringing up a topic where you don't have specialist knowledge can feel risky. But here's the truth: your clients don't expect you to be a chartered surveyor. They expect you to be their trusted advisor who spots opportunities.
How to Start the Conversation
The key is to move from a vague idea to a concrete number. Try this approach:
- Lead with a question: "Have you ever looked at whether there might be capital allowances in your property?"
- Explain the reality: "Most businesses don't claim everything they're entitled to — it's estimated that 87% under-claim."
- Offer a solution: "We have a free tool that can check your eligibility in just a couple of minutes."
- Set expectations: "It takes less time than your annual tax return meeting, and there's no obligation."
Having a Number Changes Everything
When you can present a concrete figure — "our preliminary assessment suggests you could be entitled to £45,000 in allowances" — the conversation transforms. You're no longer asking "should we look into this?" You're presenting a genuine business opportunity.
The Solution
You Don't Have to Be a Surveyor.
You Just Need the Right Tool.
Capital allowances are one of the most significant value-add opportunities you can bring to your clients. But you don't need to become a chartered surveyor to deliver these savings.
Capex Check is designed specifically for accountants. It bridges the gap between tax expertise and property surveying, giving you the ability to identify opportunities in minutes — not days.