Structures & Buildings Allowance Calculator
Calculate the SBA: 3% a year straight-line on non-residential construction costs (10% in freeport tax sites), with first-year pro-rating and tax saving.
Data verified · July 2026
What rate is the SBA?
3% per year straight-line on qualifying construction costs (33⅓-year write-off) — 10% per year in designated freeport and investment zone tax sites.
Source: GOV.UK — Claiming capital allowances for structures and buildings (gov.uk/guidance/claiming-capital-allowances-for-structures-and-buildings); freeport tax sites relief. · updated 2026
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Everything about Structures & Buildings Allowance Calculator
📋Overview+
Computes the Structures and Buildings Allowance: 3% per year straight-line on qualifying construction or renovation costs of non-residential buildings (a 33⅓-year write-off), or 10% per year in freeport and investment zone tax sites — pro-rated for the first year and converted into a tax saving at your marginal rate. Land cost never qualifies.
💡 Best practices
- Fixtures and integral features are plant & machinery — carve them out and claim the AIA or full expensing at 100% instead of 3%.
- On sale, the buyer inherits the remaining allowances, but the SBA you claimed is added to your disposal proceeds for CGT.
- An allowance statement is mandatory — without it the SBA entitlement is lost for ever.
🔢 Concrete example
£1,000,000 of qualifying construction (plus £400,000 of land, excluded), brought into use mid-year: £30,000 annual allowance (3%), £15,000 in year 1, saving £7,500 a year at the 25% CT rate.
📖User guide+
How to use this calculator
- 1
Enter qualifying construction or renovation costs (exclude land).
- 2
Mark freeport/investment zone site if applicable (10% rate).
- 3
Adjust months of use in the first year.
- 4
Read the annual allowance, first-year amount and tax saving.
📚Glossary+
- Straight-line 3%
- The same allowance every year for 33⅓ years until the full construction cost is relieved — unlike plant & machinery's reducing-balance pools.
- Qualifying costs
- Construction, renovation and conversion of non-residential structures from first non-residential use — excluding land, residential property and plant & machinery (claim AIA/full expensing for those).
ℹ️Sources & updates+
Last data update
July 5, 2026
Sources and references
GOV.UK — Claiming capital allowances for structures and buildings (gov.uk/guidance/claiming-capital-allowances-for-structures-and-buildings); freeport tax sites relief.
The data in this calculator is updated regularly to reflect the latest official rates. When in doubt, consult the official sources listed above.
FAQ — Structures & Buildings Allowance Calculator
What rate is the SBA?+
3% per year straight-line on qualifying construction costs (33⅓-year write-off) — 10% per year in designated freeport and investment zone tax sites.
Does land qualify?+
No — land acquisition costs, planning permission tied to land value and residential property never qualify. Only construction, renovation and conversion costs do.
What happens when I sell the building?+
The buyer continues claiming the remaining allowances at the same rate, and the SBA you claimed is added to your sale proceeds when computing the capital gain.