Industrial Buildings Allowance (IBA)
![]() |
The Industrial Buildings Allowance (IBA) was introduced by the government in its 1945 Income Tax Act to boost post-war productivity in industry. The idea was that whatever the capital cost of constructing a manufacturing or processing building (or sometimes purchasing it 'second-hand’), the person holding 'the relevant interest' in the building would receive tax relief.
Aimed originally at productive industry, the scope of IBA was broadened to include allowances on infrastructure such as tunnels, bridges, roads used for highway concessions, qualifying hotels and commercial buildings in enterprise zones.
In effect, IBA was a writing down allowance (WDA) – allowing relevant business people to deduct a percentage of the value of an item from their profits each year, which in turn meant they paid less tax – typically for around 25 years, sometimes less. Thus, IBA constituted an incentive to build ‘industrial’ facilities.
However, the item had to count as ‘qualifying expenditure’ that had been incurred on a building.
IBA was made to the person holding relevant interest in relation to the qualifying expenditure. The relevant interest is defined by the construction expenditure incurred on the building; relevant interest therefore is the interest in the building to which the person who incurred the construction expenditure was entitled to when the expenditure was incurred. A building may have had several relevant interests, as construction expenditure could have been incurred at different times and by different people.
The following is an example of relevant interest given by UK tax collection service Her Majesty’s Revenue and Customs (HMRC, formerly ‘Inland Revenue’ for income tax collection):
"Warren builds a factory on land that he owns. The relevant interest for the factory is the freehold interest. If Warren leases the factory to Lowell and Lowell builds an extension, the relevant interest for the extension is Lowell’s leasehold interest. So, there are two relevant interests for the factory – Warren’s freehold interest for the factory and Lowell’s leasehold interest for the extension."
Buildings or constructions that qualified were:
- Buildings of a qualifying trade: e.g manufacturing/processing, storage, generating/transforming/converting, transmitting electrical energy
- Supplying water for public consumption
- Providing sewage undertakings
- Transport, inland navigation and dock undertakings (dock, wharf, pier etc)
- Tunnels
- Bridges (only if expenditure incurred after end 1956-57)
- Highways
- Undertakings for the supply of hydraulic power.
IBA allowances no longer exist. They were continuously in force from 1945 to 2008, after which they became the subject of a phased withdrawal until the financial year beginning April 1, 2011. Since then there have been no IBA writing down allowances.
[edit] Related articles on Designing Buildings
Featured articles and news
Homes England creates largest housing-led site in the North
Successful, 34 hectare land acquisition with the residential allocation now completed.
Scottish apprenticeship training proposals
General support although better accountability and transparency is sought.
The history of building regulations
A story of belated action in response to crisis.
Moisture, fire safety and emerging trends in living walls
How wet is your wall?
Current policy explained and newly published consultation by the UK and Welsh Governments.
British architecture 1919–39. Book review.
Conservation of listed prefabs in Moseley.
Energy industry calls for urgent reform.
Heritage staff wellbeing at work survey.
A five minute introduction.
50th Golden anniversary ECA Edmundson apprentice award
Showcasing the very best electrotechnical and engineering services for half a century.
Welsh government consults on HRBs and reg changes
Seeking feedback on a new regulatory regime and a broad range of issues.
CIOB Client Guide (2nd edition) March 2025
Free download covering statutory dutyholder roles under the Building Safety Act and much more.
Minister quizzed, as responsibility transfers to MHCLG and BSR publishes new building control guidance.
UK environmental regulations reform 2025
Amid wider new approaches to ensure regulators and regulation support growth.
BSRIA Statutory Compliance Inspection Checklist
BG80/2025 now significantly updated to include requirements related to important changes in legislation.