Construction contract income uses percentage completion, with limited service contract exceptions and detailed rules for revenue and costs. Income from construction contracts and contracts for providing services is generally computed on the percentage of completion method under the ICDS framework. Limited exceptions apply for short-duration service contracts and service contracts involving an indeterminate number of acts, which are computed on the project completion method or straight line method, respectively. Contract revenue includes retention money and is recognised only when collection is reasonably certain, while contract costs cover direct, allocable, specifically chargeable and borrowing costs, subject to exclusions for unallocable costs and incidental income.