What is the difference between a variation order and a change order in UK construction?

In the UK construction industry, the term 'variation order' (VO) is the standard term used in JCT (Joint Contracts Tribunal) contracts and in general UK construction practice to describe a formal instruction to change the scope, character, or quality of the contracted works. The term 'change order' (CO) is the equivalent term used in US construction and in some international contracts. Both terms refer to the same concept: a written instruction by the employer or contract administrator authorising a change to the original contract works, whether by adding to, omitting from, or substituting elements of the works. Under JCT contracts, the definition of a 'Variation' is broad and includes: alterations or modifications to the design, quality, or quantity of the works; additions, omissions, or substitutions to the works; and changes to the obligations or restrictions imposed by the employer (for example, regarding access, working hours, or the order of works). Under both the JCT Minor Works and Standard Building Contract, the contract administrator has authority to instruct variations on behalf of the employer, and the value of those variations is added to or deducted from the Contract Sum.

How is a variation valued under a JCT contract?

Under JCT contracts, the valuation of variations is carried out by the contract administrator (or quantity surveyor) in accordance with the valuation rules set out in the contract. The primary method of valuation is to use the rates and prices in the Contract Bills (or schedule of work items if no bills of quantities exist) where the variation work is of similar character and carried out under similar conditions to that described in the original contract. Where the work is not of similar character or is not carried out under similar conditions, rates and prices in the contract may be used as a basis for valuing the variation, with appropriate adjustments. Where none of these approaches is appropriate, the variation is valued at a fair valuation — that is, at a rate that fairly reflects the contractor's actual costs plus a reasonable allowance for overhead and profit. For daywork (time-and-materials work instructed in urgent situations), the contractor should record daywork sheets and have them signed by the contract administrator or employer's representative. The valuation of variations must ultimately be reflected in the Contract Sum Account (or final account) and in the interim payment mechanism. Under HGCRA 1996, any additional sums due as a result of variations must be included in the Payment Notice.

Can a contractor be required to carry out a variation before the price is agreed?

Yes, under most standard form construction contracts in England and Wales — including the JCT Minor Works and Standard Building Contract — the contractor is generally obliged to carry out an instructed variation promptly, even if the price has not yet been agreed. The contract administrator has authority to instruct variations and the contractor must comply; failure to comply may constitute a breach of contract. However, the contractor has the right to have the variation properly valued and paid for, and this valuation process may proceed in parallel with the works. Where the contractor disputes the value of a variation, it should record all its costs (labour, materials, plant) contemporaneously and give notice of any dispute using the contract's dispute resolution mechanisms — including the right to refer the dispute to adjudication at any time under section 108 of the HGCRA 1996. In practice, it is better for both parties to agree the value of a variation before it is carried out where reasonably practicable: our Variation Order template includes space to record both the agreed value and the basis of valuation.

Does a variation order have to be in writing?

Under most standard form construction contracts in England and Wales, a variation instruction must be given in writing (or confirmed in writing) to be effective. The JCT contracts require variations to be instructed by the contract administrator in writing. An oral variation instruction may be given in an emergency, but it should be confirmed in writing as soon as reasonably practicable after it is given. Where a contractor carries out works on the basis of an oral instruction that is not subsequently confirmed in writing, the contractor may face difficulties in recovering the value of those works from the employer — particularly if the employer later disputes that the instruction was given or disputes the scope of the works instructed. A signed Variation Order is the best evidence of a properly instructed variation. It records the exact scope of the change, the agreed value, and the effect on the programme, and provides the documentary basis for the payment mechanism under the HGCRA 1996.

Can a variation order extend the contract completion date?

Yes. Where a variation causes delay to the works, the contractor is generally entitled to an extension of time to the contractual Date for Completion. Under JCT contracts, variations instructed by the employer or contract administrator are a 'Relevant Event' for extension of time purposes. The extension of time relieves the contractor of liability for liquidated damages to the extent that the delay was caused by the variation. The extension should be assessed and granted by the contract administrator as soon as reasonably practicable after the effects of the variation on the programme are known. It is good practice to agree the extension of time at the same time as the variation is instructed, if the programme implications are clear. Where the extension of time cannot be assessed immediately (for example, because the programme impact depends on the outcome of design development), it should be agreed as soon as possible after the works are completed and the programme impact can be properly assessed. Under the HGCRA 1996, a failure to grant a proper extension of time may affect the employer's right to deduct liquidated damages for delay.

What happens if the employer instructs an omission variation and gives the omitted work to another contractor?

Instructing an omission variation and then giving the omitted work to a different contractor can constitute a breach of contract by the employer in certain circumstances. The leading case is Abbey Developments Ltd v PP Brickwork Ltd [2003] EWHC 1987 (TCC), in which the court held that an employer could not use the variation mechanism to omit work from one contractor and give it to another contractor purely to get the work done more cheaply, unless the contract expressly permitted this. However, an employer may instruct a genuine omission (where it has decided not to have the work done at all, or has a legitimate commercial reason for the change) without liability. The distinction is between a genuine omission (where the decision is not to have the work done) and a transfer of work (where the omitted work is given to another contractor). If the employer instructs an omission variation and then gives the omitted work to another contractor, the original contractor may be entitled to claim loss of profit on the omitted works as damages for breach of contract.

Variation Order (UK) — United Kingdom

Issue a formal Variation Order for construction works in England and Wales. This UK construction variation order (the equivalent of a change order) records additions, omissions, and substitutions to the original works scope, the agreed financial effect on the Contract Sum, VAT treatment, extension of time implications, and compliance with HGCRA 1996 payment provisions. Used under JCT-style contracts.

What Is a Variation Order (UK)?

A Variation Order (VO) is a formal written instruction used in UK construction contracts to authorise changes to the scope, character, or quality of the original contracted works. In England and Wales, the term 'variation order' is the standard construction industry equivalent of what is called a 'change order' in the United States: both refer to the same legal mechanism for amending the works to be carried out under a construction contract.

Variation orders are an essential feature of all major UK standard form contracts, including the JCT (Joint Contracts Tribunal) suite. Under JCT contracts, a 'Variation' is broadly defined to include: additions to the works; omissions from the works; substitutions (replacing one element with another); and changes to the obligations or restrictions imposed by the employer (such as changes to working hours, access arrangements, or the order in which works are to be carried out). The contract administrator (typically an architect or surveyor) has authority under the contract to instruct variations on behalf of the employer.

From a legal perspective, variation orders are closely regulated by the Housing Grants, Construction and Regeneration Act 1996 (HGCRA 1996). Any adjustment to the Contract Sum as a result of a variation must be processed through the payment mechanism under the contract — including the Payment Notice and Pay Less Notice regime — to comply with the Act. Failure to properly document and process variations through the payment mechanism is a common source of disputes in the UK construction industry and can lead to adjudication proceedings under section 108 of the HGCRA 1996.

When Do You Need a Variation Order (UK)?

A Variation Order should be issued whenever any change is made to the scope, character, or quality of the original construction works. Changes to construction projects are extremely common: design development, client requirement changes, unforeseen site conditions, and value engineering exercises all regularly give rise to variations.

A formal Variation Order is needed in the following circumstances: when the employer or contract administrator wishes to add additional works to the original scope; when the employer wishes to omit elements of the original works; when one element of the specification is being substituted for another (for example, a change of materials or specification); when the working method or sequencing of the works is being changed; or when access restrictions, working hours, or other obligations imposed on the contractor are being varied.

Without a formal written Variation Order, both parties are at risk. The employer risks paying for works that were not properly instructed, or finding that it cannot recover the cost of unauthorised additional works. The contractor risks carrying out additional works without proper authority, and then finding that it cannot recover the full value of those works from the employer — particularly where the employer disputes the scope or cost of the variation. A signed Variation Order provides certainty for both parties about what has been instructed, what it will cost, and what effect it has on the programme.

What to Include in Your Variation Order (UK)

A well-drafted Variation Order for use in England and Wales should include several key elements that together provide a clear and enforceable record of the change to the original contract.

The variation reference and date are essential for record-keeping and for linking the Variation Order to the original contract and project. Sequential numbering of Variation Orders is important for tracking the cumulative impact of all variations on the Contract Sum and programme.

The description of the variation should be precise and comprehensive, identifying exactly what work is being added, omitted, or changed. Where the variation relates to specific drawings or specifications, those documents should be identified by number and revision. Ambiguity in the description of a variation is a frequent source of disputes about the scope of instructed changes.

The financial effect clause records the agreed value of the variation — whether it is an addition to or deduction from the Contract Sum, the amount agreed, the VAT position, and the revised Contract Sum after the variation has been applied. This information is essential for the payment mechanism under the HGCRA 1996: the agreed variation value must be included in the next Payment Notice under the contract.

The programme effect clause records any extension of time granted as a result of the variation. Where a variation causes delay, the contract administrator should grant a fair and reasonable extension of time to relieve the contractor of liability for liquidated damages attributable to that delay. The revised Date for Completion should be clearly recorded.

The supporting documents section identifies any drawings, specifications, cost estimates, or other documents that form part of the Variation Order and should be read with it.

Both parties should sign the Variation Order to confirm their agreement to its terms. A signed Variation Order is significantly easier to enforce in adjudication or court proceedings than an unsigned instruction or a disputed oral agreement.

What Is a Variation Order (UK)?

When Do You Need a Variation Order (UK)?

What to Include in Your Variation Order (UK)

Frequently Asked Questions

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