Capital allowances have just become significantly more complex — and significantly more valuable. The 2025 Autumn Budget delivered a sweeping reconfiguration of the UK’s plant and machinery regime that is now fully in force. A new 40% first-year allowance arrived on 1 January 2026. The main pool writing-down allowance dropped from 18% to 14% on 1 April 2026. Both changes interact with the permanent full expensing regime in ways that directly affect how you time capital expenditure, structure leasing decisions, and model your corporation tax forecasts.
This is not background noise. If your business buys plant or machinery, leases equipment, or operates as a partnership, these rules will change your effective cost of investment. Getting the hierarchy wrong costs real money — and HMRC will not give you a second chance to claim what you missed.
Why This Regime Change Matters Right Now
For much of the past three years, capital allowances planning centred on a simple question: does this expenditure qualify for full expensing at 100%? If yes, claim it and move on. If no, it fell into the main pool at 18% WDA — not disastrous, but not particularly exciting either.
That binary is gone. We now have three substantively different first-year relief rates — 100%, 50%, and 40% — sitting alongside a reduced WDA of 14%. The gap between taking accelerated relief and letting expenditure fall into the pool has widened materially: you are now choosing between a 100% (or 40%) deduction in year one versus 14% annually on a declining balance. For a company paying corporation tax at 25%, that differential in timing translates directly into a cash tax deferral — and in the current interest rate environment, that deferral has real present value.
The New 40% First-Year Allowance: What It Is and Who It Benefits
The 40% first-year allowance applies to expenditure on new and unused plant or machinery that qualifies for the main rate of writing-down allowance, incurred on or after 1 January 2026. Cars are excluded. The 60% balance enters the main pool and attracts WDA thereafter.
On the face of it, 40% looks modest compared to 100% full expensing. But the critical point is who can claim it. BDO’s capital allowances guidance makes the position clear: full expensing is available only to companies within the charge to corporation tax. The new 40% FYA extends to two groups that were previously left behind:
- Lessors of plant and machinery — large leasing businesses providing equipment for UK use were largely excluded from full expensing. The 40% FYA now gives them meaningful upfront relief, and as KPMG notes, the benefit can flow through to reduced lease costs for lessees.
- Unincorporated businesses — sole traders and partnerships now have access to a proper first-year allowance on main-pool expenditure above the AIA cap. For mixed partnerships (where individual partners cannot access the AIA), this is particularly valuable.
There is, however, an important gap: no equivalent 40% FYA exists for special-rate expenditure. Long-life assets, integral features, and other special-rate items remain outside the new relief. If you are investing in high-value fixtures, electrical systems, or heating infrastructure, the 6% special-rate pool WDA is still the backstop — unless the AIA covers the spend within its £1 million annual cap.
The WDA Reduction From 18% to 14%: Why It Changes Every Calculation
From 1 April 2026, the main pool writing-down allowance falls from 18% to 14%. The Saffery practical guide confirms the mechanics: this applies on a reducing-balance basis after any first-year allowance claims, and a hybrid rate operates for accounting periods that straddle the 1 April date.
The practical consequence for CFOs is threefold:
- Tax relief takes longer. Under the old 18% WDA, you recovered roughly 50% of main pool cost within four years. At 14%, the same recovery takes around five to six years. For large capex programmes, the NPV difference in deferred tax relief is material.
- The premium on accelerated relief has increased. KPMG puts it plainly: “the differential between the 100 percent FYA and the 14 percent WDA is now even greater.” Every pound of qualifying expenditure that misses full expensing because a project straddled a year-end — or because the asset was not correctly categorised as main-pool — now costs more in deferred tax.
- Period-end timing is more sensitive. Where you have qualifying expenditure near a year-end, the decision about whether to incur it before or after the period closes can shift the first-year relief by 86 percentage points (100% full expensing versus 14% WDA). That gap is worth modelling explicitly, not leaving to accounting convention.
The Full Hierarchy: Which Allowance Takes Priority?
Drawing on the PwC UK tax summary and the UK Tax Policy Map’s 2026 changes guide, the claiming hierarchy that should now sit in every capital expenditure analysis looks like this:
- Annual Investment Allowance (£1m cap) — 100% relief, available to all businesses, all qualifying assets except cars. Use this first for special-rate expenditure and second-hand assets where FYAs are unavailable. Shared across group companies — allocate deliberately.
- Full expensing (100% FYA) — companies only, new and unused main-pool assets. The default choice for any company with qualifying capex in this category.
- 50% special-rate FYA — companies only, new and unused special-rate assets (integral features, long-life assets). The remaining 50% enters the special-rate pool at 6% WDA.
- 40% FYA — lessors of main-pool assets and unincorporated businesses, on expenditure from 1 January 2026. The remaining 60% enters the main pool at 14% WDA.
- Main pool WDA at 14% — the default for anything that does not qualify for or has not been claimed under items 1–4.
- Special-rate pool WDA at 6% — the default for special-rate assets outside FYA or AIA cover.
You cannot claim both full expensing and the 40% FYA on the same asset. Where both AIA and FYA are theoretically available, 100% full expensing beats 40% FYA on any objective NPV analysis — the only reason to prefer AIA is group-level sharing constraints or asset eligibility differences.
Disposal Rules: The Claw-Back Most Finance Teams Overlook
One area that tends to catch finance teams off guard is what happens when an asset on which full expensing (100% or 50% FYA) was claimed is subsequently sold. BDO’s disposal guidance is explicit: disposal proceeds create an automatic balancing charge, taxable at the prevailing corporation tax rate. Unlike assets that flowed through the pool, there is no pooled balance to absorb the disposal value.
This matters most in M&A contexts. If a target company has claimed full expensing on a substantial fleet of equipment or leasehold improvements, and those assets are being sold or transferred as part of a deal, the embedded balancing charges need to be surfaced in due diligence and priced into the consideration. Note that the 40% FYA does not create this same claw-back exposure — assets claimed at 40% enter the pool for the remaining 60%, and normal pool disposal mechanics apply.
For property transactions, the s198 election under the Capital Allowances Act 2001 remains essential: sellers and buyers must pool fixture expenditure and fix values within two years of completion, or the buyer loses the right to claim entirely. Given the widened gap between first-year relief and the 14% WDA, the cost of missing a s198 election has increased materially compared to the pre-Budget position.
Leasing: A Changed Landscape Worth Revisiting
The 40% FYA changes the economics of equipment leasing in a way that deserves more attention than it is currently getting in most boardrooms. Prior to 1 January 2026, a leasing company providing assets to UK businesses could not access full expensing — excluded because the assets were being used for leasing. Relief was restricted to the 18% WDA (now 14%), making UK lease financing materially less tax-efficient than straight asset purchase by the lessee.
The 40% FYA partially corrects this. KPMG observes that lessors can now factor the improved allowance into their lease pricing, potentially sharing the benefit with lessees through lower rental rates. For CFOs evaluating lease-versus-buy decisions on significant equipment, the post-January 2026 numbers look different from the analysis you ran eighteen months ago. The operational advantages of leasing — flexibility, maintenance bundling, off-balance-sheet treatment under certain structures — may now come at a lower after-tax cost than previously modelled.
Eight CFO Actions Before Your Next Capital Budget
- Audit your capex pipeline by asset class. Separate main-pool from special-rate expenditure. Confirm which assets qualify as new and unused. Cars, second-hand assets, and overseas-leased items are excluded from FYAs — identify them before you allocate relief.
- Remodel your corporation tax forecast with 14% WDA. For companies with significant un-pooled balances — second-hand assets, special-rate items, or assets that missed FYA claims — the timing of tax relief has extended. That affects your effective tax rate and forward cash tax payments.
- Review large projects for period-end timing. For capex programmes near your year-end, assess whether incurring expenditure before versus after the period close changes the first-year relief available. The 86-percentage-point gap between full expensing and WDA makes this a genuine optimisation exercise. Review in-period rather than waiting for project completion.
- Manage your group’s AIA allocation deliberately. A single £1 million AIA is shared across all companies in a group or under common control. Concentrate AIA where no FYA is available — particularly on special-rate assets and second-hand acquisitions — rather than applying it at random across entities.
- Update lease-versus-buy models. Ask your lessors whether they are pricing in the 40% FYA benefit. If they are not, or if their assets do not qualify, the balance of the analysis may still favour purchase. If they are passing on the benefit, the economics of leasing have improved.
- Build a disposal register for full expensing claims. Every asset claimed under full expensing (100% or 50% FYA) that sits outside the main or special-rate pools creates a potential balancing charge on disposal. This register is a balance sheet exposure that needs to be visible to your audit committee and factored into any asset disposal planning.
- Update M&A due diligence checklists. Capital allowances due diligence needs to reflect the new regime. Surface full expensing claims in targets, quantify embedded balancing charges on planned asset disposals, and verify s198 elections on commercial property fixtures. The Finance Act 2026 changes make this more consequential than it was pre-Budget.
- Assess R&D Allowances for qualifying capex. Where expenditure is incurred on assets used exclusively for qualifying R&D activities, 100% Research and Development Allowances may be available regardless of the main-pool FYA position. Lab equipment, test rigs, and prototyping assets all warrant assessment as a parallel claim.
The Finance Act 2026 Context
The capital allowances changes sit within a broader set of Finance Act 2026 reforms that received Royal Assent on 18 March 2026. The government’s stated intention is to maintain a competitive investment environment — keeping full expensing permanent and introducing the 40% FYA — while raising revenue through the WDA reduction. The logic is that accelerated front-loading via FYAs costs the Treasury less in NPV terms than permanent pool balances yielding relief indefinitely at 18%.
The zero-emission car and EV charging point 100% FYA has been extended to 31 March 2027 (corporation tax) and 5 April 2027 (income tax) — a useful window if your fleet programme includes EVs. For businesses operating in Freeport or Investment Zone special tax sites, 100% FYA is available on qualifying plant and machinery within the designated area, alongside an enhanced 10% WDA on structures and buildings — the interaction with the main-pool rules needs specific modelling.