A variation or change in scope clause is defined in construction contracts to take care of situations arising from change in the defined scope of work. Such changes may arise due to factors such as additions or deletions in the scope of work, modifications in the type, grade or specifications of materials, alterations in specifications or drawings, and acts or omissions of other contractors. Further, ineffective planning, inadequate investigations or surveys and requests from the employer or those within the project’s area of influence can contribute to changes in the scope of work. External factors such as unavailability of the materials required, weather conditions or evolving technology can also necessitate variations in construction contracts. Variations may also result from changes in law, adjustments to the contract schedule, unforeseeable physical conditions and revisions in detailed design. In NTPC Ltd v. Tata Projects Ltd, O.M.P. (COMM) 59/2023, unforeseen soil conditions were encountered during the construction of induced drought cooling towers, which led to additional excavation work and increased costs. The Delhi High Court upheld the costs granted by the tribunal to the contractor due to unforeseen soil conditions leading to additional excavation work and increase in cost, and held that the award of costs for additional excavation works does not suffer from any infirmities or patent illegality.Clause 13 of the FIDIC Yellow Book (1999) sets out the procedure for managing variations, including their instruction, valuation and implementation. The engineer has the authority to order changes, while the contractor may suggest modifications to enhance efficiency subject to approval by the engineer. If a variation impacts the contract price or completion period, the contractor is entitled to an adjustment for changes in cost and time under Clause 13; however, the procedure given in Clause 20, Claims, Disputes and Arbitration, including timely notification and submission of details to secure compensation or an extension of time is required to be followed. Similarly, under Clause 13 of the FIDIC Silver Book, the employer has the sole authority to issue variations. However, the contractor must comply with the prerequisites given in Clause 20, including timely notification and supporting details of additional time and cost, if any; otherwise, the claim may be forfeited. Clause 13 of FIDIC Red Book (1999) governs variations and outlines the process for instructing, valuing and implementing changes in the scope of work under the contract. While the engineer has the authority to issue variation, the contractor can propose variations aimed at improving efficiency, subject to approval of such variation and consequent additional time and cost, if any, by the engineer. While emphasising upon the requirement of following contractual procedure, the Delhi High Court in NHAI v. Pati-Bel (JV) O.M.P. (COMM) 314/2017 held that for a contractor to be entitled to additional costs under the variation clause, the work must have been specifically instructed either by the employer or the engineer. If a contractor undertakes additional work voluntarily without such an instruction, they cannot later claim compensation for it.Variations in construction projects can significantly impact both time and cost of the project, often causing delays in completion and increase in expenses incurred for the completion of project. In order to prove additional time on account of Variation, a robust ‘forensic schedule delay analysis’ following the principles of SCL Delay & Disruption Protocol 2017 is sine qua non. Use of additional materials, extended labour hours and prolonged equipment use escalate project expenses, while indirect costs such as site maintenance, administrative overheads and rework further strain budgets. Accurate recordkeeping, including invoices, supplier quotations and expenditure logs, is crucial for supporting claims and preventing disputes over additional costs. A quantum analysis considering both direct and indirect expenses is essential in determining financial impact due to variation. In NHAI v. Oriental Structure Engineers Pvt Ltd FAO(OS) NO.461/2012, NHAI challenged an arbitral award under Section 34 of the Arbitration and Conciliation Act, 1996, disputing the tribunal’s valuation of variations. The Delhi High Court dismissed NHAI’s objections, emphasising that variations must be valued strictly in accordance with the contract.In THDC India Ltd. v. M/s PCL Intertech Lenhydro Consortium JV 2024(2) ARBLR 537 (Delhi) (DB), the Supreme Court dealt with an issue regarding delay in project on account of extra works done by the contractor and upheld the award for the cost incurred due to extra works beyond the scope of works under the contract. Recently, the Delhi High Court in NHPC Ltd v. Hindustan Construction Company Ltd and Ors. 2024(1) ARBLR 422 (Delhi High Court), upheld the arbitral award granting costs for works executed which was beyond the original scope  of works as well as the costs  for reduction in original scope of works.In a nutshell, to take care of additional time and costs required to execute the variation, the contractor is required to follow the procedure given in the contract, including relating to timely notification of effect of variation on the project timelines and project cost. The engineer/employer is also required to ensure that the change of scope orders are issued in time and the contractor’s requests vis-a-vis time and costs on account of variation orders are decided promptly as per the provisions of the contract to ensure that the project does not suffer from time and cost overruns. All parties to the contract must follow the provisions of contract regarding variations in order  to iron out possibilities of any future disputes.