Capital Allowances Calculator
Plan writing down allowances over up to 10 years: 18% main pool, 6% special rate pool, 100% zero-emission car FYA and the small pools write-off.
Data verified · July 2026
What are the writing down allowance rates?
18% a year (reducing balance) for the main pool and 6% for the special rate pool — integral features, long-life assets and cars over 50g/km CO2.
Source: GOV.UK — Work out capital allowances (gov.uk/work-out-capital-allowances); capital allowances on cars. · updated 2026
Like this calculator?
Create a free account to save your calculations, access history, and export to PDF. Upgrade to Pro for all 319 calculators.
A question about this result?
Ask Solva, ActioFin's AI finance advisor — answers sourced from official texts.
5 free questions per day with a free account
Everything about Capital Allowances Calculator
📋Overview+
Projects writing down allowances on plant & machinery pools: 18% a year reducing balance on the main pool, 6% on the special rate pool (integral features, long-life assets, high-emission cars), 100% first-year allowance on new zero-emission cars, and the £1,000 small pools write-off — with the multi-year tax saving at your marginal rate.
💡 Best practices
- New qualifying spend usually does better through the AIA or full expensing (100% year 1) — use the WDA pools for what they cannot cover.
- Cars are pooled by CO2: ≤50g/km new electric cars get a 100% FYA, others go to the main (≤50g used) or special rate pool (>50g).
- Claiming less WDA than the maximum is allowed — useful to preserve allowances against future profits.
🔢 Concrete example
£100,000 main pool, £50,000 special pool and a £40,000 new electric car at 25%: year-1 allowances £61,000 (£18,000 + £3,000 + £40,000 FYA), saving £15,250 — about £116,231 of allowances over 5 years.
📖User guide+
How to use this calculator
- 1
Enter opening balances and this year's additions for each pool.
- 2
Add any new zero-emission car cost (100% first-year allowance).
- 3
Set your marginal tax rate and the projection horizon.
- 4
Read year-1 allowances and the cumulative picture.
📚Glossary+
- Reducing balance
- Each year's allowance is a percentage of the remaining pool: £100,000 gives £18,000 in year 1, £14,760 in year 2, and so on — never quite reaching zero without the small pools rule.
- Small pools allowance
- When a pool balance is £1,000 or less at the start of a period, the whole balance can be written off at once.
ℹ️Sources & updates+
Last data update
July 5, 2026
Sources and references
GOV.UK — Work out capital allowances (gov.uk/work-out-capital-allowances); capital allowances on cars.
The data in this calculator is updated regularly to reflect the latest official rates. When in doubt, consult the official sources listed above.
FAQ — Capital Allowances Calculator
What are the writing down allowance rates?+
18% a year (reducing balance) for the main pool and 6% for the special rate pool — integral features, long-life assets and cars over 50g/km CO2.
Which cars get 100% relief?+
New zero-emission cars qualify for a 100% first-year allowance. Used electric cars and cars up to 50g/km join the 18% main pool; higher-emission cars the 6% special pool.
What is the small pools allowance?+
A pool worth £1,000 or less at the start of the period can be written off entirely instead of dragging on at 18% or 6% for ever.