Six steps to a variation order that gets paid

In short

JCT calls them variations and NEC calls them compensation events, and both make timing a condition of entitlement - NEC clause 61.3 gives eight weeks from awareness. Getting an approved variation into the next interim application, rather than the final account, is what puts it under the payment notice rules in Part II of the Construction Act.

A variation gets paid when three things happen: it is notified inside the window the contract sets, it is priced by the contract's own valuation rules, and it reaches the next interim payment application instead of being saved for the final account. Miss any one of them and the work is still done, still costed and still yours to fund, which is how a scope change becomes a write-off six months later.

What the contract calls it depends on which form you signed. JCT sets the change out under its Variations clauses. NEC calls the same territory compensation events and prices them differently. The sequence below works under either, and the definition of a variation order - including why North American contracts say change order instead - sits on its own page.

What your contract calls it, and how it values it

Under NEC, clause 60.1 of the Engineering and Construction Contract lists 21 compensation events. The cost impact is assessed on the effect the event has on the cost of work already done and the forecast cost of work not yet done at the dividing date, which is usually the point the project manager instructed the change. That is an actual-cost basis, so it is not capped by the rates you tendered.

The notice period is the trap. NEC clause 61.3 gives a contractor eight weeks from becoming aware of an event to notify it, seven for subcontractors, and a contractor who misses that window loses the right to extra time and extra money regardless of the merits. NEC's own guidance sets out one exception worth knowing: the time bar does not apply to compensation events the project manager was required to notify under clause 61.1, because the project manager should already know about events arising from their own instructions.

JCT works the other way round. Its valuation rules generally start from rates already in the contract documents, so check whether yours requires a variation to be priced at contract rates before moving to fair market rates. That hierarchy sets your recovery ceiling, and it is worth reading before you submit rather than after the quantity surveyor queries it.

Six steps from instruction to payment

The sequence is the same on a two-day job and a two-year programme. Only the paperwork scales.

1. Flag the change the day it appears. As soon as work falls outside the contract scope, say so in writing. Do not absorb it into the job cost, and do not assume it will be settled at the end. Both parties still have a clear memory of what was agreed in week one; neither does at final account.
2. Notify inside the contract's window. Under NEC that is eight weeks from awareness. Under JCT and bespoke forms it is whatever the contract says, and the contract will also name who the notice goes to - the contract administrator, the architect, the employer's agent. Send it to the named person, in writing, and keep the sent copy.
3. Price it under the contract's own rules. Show labor hours separately from materials, referenced to your contract rates, and state the basis where no equivalent rate exists. If the change extends the programme, price that impact as its own line rather than burying it in the rate - a variation covering only the direct cost underprices the change every time.
4. Get written authorization from the person the contract names. Under JCT forms the power to instruct variations sits with the contract administrator, not the main contractor's site manager, and an instruction from the wrong person may not bind anyone to pay it. If urgency forces a start, issue a written record that work is proceeding pending formal approval and keep it on the job file.
5. Log it against the job. Instruction date, notice date, pricing submission date, approval date, approved value, and the drawing or instruction reference it came from. This is the record that settles the argument later, and it has to exist before the argument starts.
6. Put it in the next interim application, not the final account. Approved variations belong in the payment cycle as separate line items carrying the variation number and the instruction date. Holding them back is the single most expensive habit in the list, for the reason in the next section.

The payment application is where variations get won

Part II of the Housing Grants, Construction and Regeneration Act 1996 is the reason a payment application is worth more than an invoice. Section 109 entitles a party to a construction contract to stage or periodic payments unless the work is specified or agreed to last less than 45 days. Section 110 requires every construction contract to provide an adequate mechanism for what becomes due and when, plus a final date for payment.

Section 110B is the provision most subcontractors have never read. Where the payer is required to give a payment notice and fails to, and the payee has already made an application for payment as the contract permits, that application is treated as the payee's payment notice. Section 111 then requires the payer to pay the notified sum by the final date for payment unless a pay less notice is served in time. In other words, a variation that is inside your application and goes unanswered becomes the sum they have to pay.

JCT translates those sections into short, unforgiving dates. Under the Standard Building Contract the interim certificate must be issued within five days of the due date, the maximum section 110A allows. The final date for payment of each interim payment is 14 days from its due date, and a pay less notice must reach the contractor no later than five days before that. Payment periods at each tier are designed not to exceed 30 days, and the interim valuation date system introduced in 2016 exists so main contract and subcontract valuations fall on the same date each month.

Two more sections are worth knowing before a dispute, not during one. Section 112 gives the payee the right to suspend performance for non-payment on at least seven days' written notice, and makes the party in default liable for the reasonable costs of the suspension. Section 113 makes pay-when-paid clauses ineffective unless the third party is genuinely insolvent, so a main contractor telling a subcontractor on a construction project that they will be paid when the client pays is, in most cases, describing something the Act does not allow.

Capture the instruction on site the day it is given

Most variations start as a sentence on site, and entitlement dies between that sentence and a written record. A same-day email to the main contractor is enough: further to today's instruction from a named individual, we will proceed with the described change, we consider it a variation to the sub-contract, and a priced variation order will follow. Keep it neutral and factual. Most main contractors will not dispute it in the moment, and if they do, you have found that out in week one.

Where the change cannot be measured against a contract rate, it is valued as daywork, and a daywork sheet only holds up if it is signed by the main contractor's representative on the day the work was done. It should record the date, the operatives' names and trades, start and finish times, the specific work and where it sits on the drawings, materials by delivery note reference, and any plant used. One named person on site owns generating and chasing those signatures. Shared across the team, sheets get missed.

Both of those are phone jobs rather than office jobs, which is the practical case for capturing the sign-off on site instead of on paper that travels back with the van. The instruction, the signature and the photographs land against the job the same day, and the priced works order is raised from a record that already exists rather than reconstructed from a WhatsApp thread.

The register, and the final account it feeds

A variation register is the commercial record that defines what you can claim. Every entry needs a unique variation reference, a description of the change, the date it was identified or instructed, the name and role of whoever instructed it, the value claimed, the status - submitted, agreed, disputed or withdrawn - and the drawing or instruction reference behind it. Entries go in when a change is identified, not when it is agreed.

Share it with the main contractor's commercial team every week or two, not at practical completion. Regular sharing forces early acknowledgement of each item and surfaces disagreements while the evidence still exists. An argument about a cable route change is settled in ten minutes when both parties can walk to the location. Six months later, with the ceiling boarded over and the site team dispersed, the same argument is unwinnable.

A final account built from that register should carry the original contract sum, every agreed variation at its approved value, every disputed variation with the value claimed and the grounds, daywork agreed and daywork submitted but not agreed with the sheets attached, any fluctuation claim the contract provides for, and any loss and expense from delay or disruption caused by others. Compiled from live records it is a document. Compiled from memory and email threads it is a negotiating position.

Timing matters at the end as much as at the start. Under standard JCT forms the final certificate becomes conclusive after a prescribed objection period, and once it does, arguments about valuations, variation entitlement, extension of time and loss and expense are very hard to reopen outside adjudication. Retention is released in two halves, at practical completion and at the end of the defects liability period, and the Small Business Protections Bill that entered Parliament on 19 May 2026 proposes banning the withholding of retention payments under construction contracts altogether. Until that lands, a final certificate you disagree with is something to deal with in the week it arrives.

Sources

• Housing Grants, Construction and Regeneration Act 1996, Part II: Construction contractsPrimary sourcelegislation.gov.uk · accessed 2026-09-10
• Housing Grants, Construction and Regeneration Act 1996, section 110B: Payment notices given by payeePrimary sourcelegislation.gov.uk · accessed 2026-09-10
• Housing Grants, Construction and Regeneration Act 1996, section 112: Right to suspend performance for non-paymentPrimary sourcelegislation.gov.uk · accessed 2026-09-10
• JCT Explains... Interim PaymentsPrimary sourceThe Joint Contracts Tribunal · accessed 2026-09-10
• Introduction to JCT Standard Building Contract: VariationsPrimary sourceThe Joint Contracts Tribunal · accessed 2026-09-10
• Compensation events: an introduction for new NEC usersPrimary sourceNEC Contracts · accessed 2026-09-10
• Dictionary of terms: compensation events and Defined CostPrimary sourceNEC Contracts · accessed 2026-09-10
• Compensation event time barsPrimary sourceNEC Contracts · accessed 2026-09-10
• Largest crackdown on late payments in over 25 years as landmark Bill enters ParliamentPrimary sourceGOV.UK · accessed 2026-09-10