First, the costs that qualify as plant and machinery are identified. Integral features, such as lifts, space and water heating, air-conditioning, hot and cold water systems (but not toilet and kitchen facilities) and electrical systems, go into the special rate pool, while most other qualifying plant and machinery goes into the main pool. For each pool, the closing balance from the last period is increased by qualifying purchases and reduced by the value of disposals. The pool’s rate is applied to that adjusted balance, the allowance is deducted, and the remainder is carried forward as the next period’s opening balance. Some expenditure may instead qualify for the Annual Investment Allowance or, for companies only, full expensing or the 50% first-year allowance, but the same expenditure cannot be claimed under more than one allowance. The tax value depends on the allowance used, the claimant’s tax position and timing, so an independent specialist can work through the figures with your accountant.