Unpaid variations (change orders) in the UK: the complete guide for subcontractors

Published 10 October 2026 · Updated 10 October 2026 · VariationFlow

How UK specialist subcontractors get variations paid, from the instruction to the final account: what counts as a variation (a change order in American terms), notifying inside the NEC4 subcontract and JCT time limits, pricing and submitting, the Construction Act payment and pay less notices, interest, suspension and adjudication when it is not paid, and the records that decide it.

If you have searched for how to get an unpaid change order paid in the UK, you are in the right place under a different name. Change order is the American term. UK contracts call it a variation (JCT and most bespoke subcontracts) or a compensation event (NEC). The money is just as real, and the rules for getting it paid are set by your subcontract and the Construction Act.

This guide runs from the moment a change is asked for to the final account, in the order things go wrong. Each step links to a fuller guide.

Is a change order the same as a variation?

In substance, yes: a change to the work you contracted to do, instructed by the party above you, that you are entitled to be paid for. The differences are in the words and the process. Under JCT the instructed change is a Variation, valued against the contract rates. Under NEC4 there are no variations at all: a change to the Scope is one of a list of compensation events, assessed on cost and time together, with strict time limits for notifying it. What is a variation in construction? covers the definitions, and JCT variations vs NEC compensation events sets the two side by side.

Why do variations go unpaid?

Rarely because the work was not done. Variations are lost when the change is never written down, submitted late or never, has no price on it, or cannot be proved when it is challenged months later at the final account. Why variations go unpaid walks through the five process failures that come up again and again. Every step below closes one of them.

Step 1: Make sure it is a variation, and get the instruction in writing

Before anything else, two questions. Is this a change to the work you priced, or work your package already included? And did someone with authority under your subcontract ask for it? Extra work requested by a site manager who has no power to instruct is a commercial risk, however willing everyone is on the day.

Most standard forms are deliberately hostile to purely verbal instructions. If the instruction was given out loud, make it written the same day with a confirmation of verbal instruction: a short note to the instructing party recording what was asked, by whom and when. It puts the burden on them to say at the time that it was not said. Verbal instructions in construction covers what the forms require and what to do when nobody will put it in writing, and variation vs claim explains why an instructed change and a claim for disruption are different routes to money.

Step 2: Notify inside the contract’s time limit

This is where entitlement is lost outright rather than argued down. On the NEC4 Engineering and Construction Subcontract, a compensation event the Contractor has not notified must be notified within seven weeks of becoming aware of it under clause 61.3. Miss that and, unless the event is one the Contractor should have notified itself under clause 61.1 (an instruction, a changed decision or a corrected assumption), there is no change to the Prices, the Subcontract Completion Date or a Key Date. On the main contract the period is eight weeks, and Z clauses commonly shorten the subcontract’s seven to four or two. Read your own amendments before you rely on any number: what is a Z clause? shows where to find them.

JCT forms have no forfeiting bar like clause 61.3 for the variation itself, but an instruction given orally has no immediate effect until it is confirmed in writing under the contract’s own procedure, and recovery of loss and expense turns on a notice given as soon as the effect on progress becomes reasonably apparent, and a late notice is the first thing the other side will point to. The guide to NEC4 compensation events sets out the whole NEC procedure.

Step 3: Price it and submit it formally

A variation with no price is an invitation to value it later, on someone else’s terms. Under JCT the starting point is the contract rates and prices, then pro-rata or fair rates, and daywork where the work cannot properly be valued by measurement. Under NEC4 the quotation is assessed on the effect on Defined Cost plus the Fee, with any delay to the completion date in the same quotation. How to value a construction variation covers both, and what is a daywork sheet? covers the record that turns extra hours into money.

Then submit it as a dated, referenced document, not a line in an email thread. On the NEC4 subcontract the clock keeps running after you submit: the quotation is due within two weeks of being instructed to give one, the Contractor has four weeks to reply under clause 62.3, and if it does not you can notify the failure; if the silence runs on for a further three weeks the quotation is treated as accepted (clause 62.6). That only helps someone who is counting.

Step 4: Put it in the application, and watch the notices

A variation is paid through your payment application like any other work. The Construction Act then sets the timetable. The contract must provide for a payment notice, usually given by the payer or someone acting for it, no later than five days after the payment due date, stating the sum considered due and how it was calculated. If none is given, your own application can become the notified sum by default. If it wants to pay less than the notified sum it must serve a pay less notice no later than the prescribed period before the final date for payment: whatever your contract says, or seven days under the Scheme for Construction Contracts where it says nothing. A pay less notice served a day late is void, and the notified sum is payable in full.

The days are counted under section 116 of the Act, not rolled to the next working day: weekends count, and Christmas Day, Good Friday and bank holidays do not, so a deadline can fall on a Saturday. The guides on payment applications that stand up, the notified sum, pay less notices and how days are counted go into each.

Step 5: When it still is not paid

There is a ladder, and it is worth climbing in order:

1. Chase in writing, citing the application, the notices served or not served, and the final date. A clear letter that shows you know the dates often settles it.
2. Claim statutory interest. Where the contract gives no substantial remedy for late payment, the Late Payment of Commercial Debts (Interest) Act 1998 gives interest at eight per cent over Bank Rate, fixed at the half-year reference date, plus a fixed sum of £40, £70 or £100 per debt. Interest on a late construction payment shows how.
3. Suspend. Section 112 gives a right to suspend the work for non-payment of the notified sum by the final date, after at least seven days’ written notice of intention stating the grounds. On contracts made since 1 October 2011 in England and Wales (1 November 2011 in Scotland) you can suspend part of the work rather than all of it. Downing tools lawfully covers the notice and the mistakes that turn a lawful suspension into a repudiation.
4. Adjudicate. Every construction contract under the Act carries the right to refer a dispute to adjudication at any time. The referral follows within seven days of the notice of adjudication, and the decision is due 28 days after the referral, or 42 if the referring party agrees, longer only if both parties do. Where the payer missed its notices, a smash-and-grab adjudication claims the notified sum; where the value of the variation itself is in dispute, it goes to a true value adjudication. Adjudication for subcontractors covers the clock, the cost and enforcement.

Step 6: Do not let the final account write it off

The final account is where unrecorded variations are traded away to close the account, and where contra-charges and defects deductions appear for the first time. Two clocks matter. The contractual one is short: 28 days to challenge a JCT Final Certificate under clause 1.9 of the main contract, the window clause 53 of an NEC4 subcontract sets to dispute a final assessment, and whatever your own subcontract says about its final payment, which can be shorter. Miss it and the figure can become conclusive. The statutory one is long: a claim for money due under a contract can be brought within six years of the date it fell due, twelve where the contract was executed as a deed. Closing a final account covers the order to negotiate in, and what is a contra-charge? covers the deductions.

The records that decide it

Every step above is won or lost on a record made at the time. The ones that settle most disputes:

• The instruction, or your written confirmation of a verbal one, dated and addressed to the person who gave it.
• Photographs and notes from the day, with the location and who asked, kept where the office can find them rather than on one operative’s phone.
• The notification, with the date you became aware of the event, where the contract has a time limit.
• The priced submission and the reply, or the record that no reply came.
• Signed daywork sheets for work that cannot be measured.
• Each payment application and every payment and pay less notice received, with the dates they arrived.

What about Northern Ireland?

Part II of the Construction Act does not extend to Northern Ireland. A job whose site is there is on the Construction Contracts (Northern Ireland) Order 1997 instead, with the same periods counted a different way. Construction payment in Northern Ireland explains the difference.

This guide is general information, not legal advice. Whether a change is a variation, which notices your contract requires and what its periods are all turn on the words of your own subcontract and any amendments to it, and are worth an adviser’s eye before a deadline is relied on.