A Writing Down Allowance (WDA) is available for plant and machinery expenditure that exceeds the Annual investment allowance (AIA) and / or does not qualify for a First-Year Allowance as well as for residual balances of expenditure that has been carried forward from the previous accounting period. The WDA is based on the cost of the items in the year they are acquired.

There are two rates of WDA for plant and machinery. To calculate them, you first group your expenditure into separate capital allowance pools:

• the main pool - this includes expenditure on most items - the rate is 18%
• the special rate pool includes special rate expenditure including long-life assets, integral features, certain thermal insulation and some cars - the rate is 6%.

Integral features are:

• lifts, escalators and moving walkways
• space and water heating systems
• air-conditioning and air cooling systems
• hot and cold water systems (but not toilet and kitchen facilities)
• electrical systems, including lighting systems
• external solar shading

It is important to note that the capital allowances regime for integral features only applies to the above list and that buildings themselves don’t qualify for capital allowances. However, before you make a claim (or not) for integral features please speak to us as the rules can be complicated and there are many grey areas.