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.
🧮
Fill in the fields to see results in real time
Create a free account to save your calculations, access history, and export to PDF. Upgrade to Pro for all 319 calculators.
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.
£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.
Enter qualifying construction or renovation costs (exclude land).
Mark freeport/investment zone site if applicable (10% rate).
Adjust months of use in the first year.
Read the annual allowance, first-year amount and tax saving.
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.
3% per year straight-line on qualifying construction costs (33⅓-year write-off) — 10% per year in designated freeport and investment zone tax sites.
No — land acquisition costs, planning permission tied to land value and residential property never qualify. Only construction, renovation and conversion costs do.
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.