What to look for in NEC and JCT variation software: ten questions to ask before you buy
Published 10 October 2026 · Updated 10 October 2026 · VariationFlow
A buyer’s checklist for UK specialist subcontractors choosing variation management software for NEC4 and JCT work: subcontract periods rather than main contract ones, Z clauses, Construction Act day counting, which side of the payment notice the tool serves, capture on site without signal, getting the instruction in writing, chasing, evidence, exporting your data and price.
Almost any system can store a variation. The test of software for NEC and JCT work is whether it knows what the contract does to that variation: when it must be notified, when the reply is due, what a missed notice means for the money. Ask these ten questions of every tool on your list, including ours, and ask to see the answer on a real project rather than a slide.
The contract
1. Does it use the subcontract’s periods, or the main contract’s?
We serve subcontractors, and the subcontract forms have their own numbers. On the NEC4 Engineering and Construction Subcontract the clause 61.3 bar for notifying a compensation event is seven weeks; on the main contract it is eight. A tool that quietly uses the main contract’s figure gives you a deadline a week after your entitlement has gone. Ask which form each period comes from, and what it does when the form is not known: the safe answer is the shorter period.
2. Can you record a Z clause that changes a period?
Z clauses commonly shorten the subcontract’s seven weeks to four or two. If the tool cannot hold your project’s own figure, every date it shows on that job is wrong in the direction that costs money. What is a Z clause? explains where to find them.
3. Does it count Construction Act days the way the Act does?
Section 116 excludes Christmas Day, Good Friday and bank holidays from the count, and nothing else. Weekends count, so a pay less deadline can fall on a Saturday, and a tool that rolls it to the Monday makes a late notice look timely. Scotland’s bank holidays differ from England’s, and a site in Northern Ireland is under a different Order with a different way of counting. Ask which holiday calendar a project uses and how it is chosen. How days are counted has the detail.
4. Which side of the payment notice does it serve?
Some payment tools are built around the party paying, to help it serve its notices on time. A subcontractor needs the opposite view: the deadlines the payer must meet, and what follows when it misses them. With no valid payment notice your application can become the notified sum, and with no valid pay less notice in time the notified sum is payable in full. Ask whether it tells you, as the payee, when a pay less notice arrived too late. The notified sum explains why that is the number that matters.
5. Does it tell you when it does not know?
A JCT sub-contract sets its own payment periods, which are not the main contract’s. Software that assumes the main contract’s figures will put a pay less deadline on the wrong day and pronounce a notice late or on time on that basis. The better answer is a tool that asks for your subcontract’s own periods and gives no verdict until it has them.
The variation
6. Can the person who meets the change record it on site, without signal?
Most variations start on site, out loud. The record that wins them is made in the first hour: what changed, who asked, photographs, the location and ideally the requester’s signature. Ask whether the site team can capture that on a phone in a basement with no signal, in their own language, and whether it reaches the office without anyone retyping it. Verbal instructions shows why the first hour matters.
7. Does it get the instruction in writing?
A variation the main contractor never answered is one person’s word against another’s. Ask how a submission reaches the main contractor, whether they can reply without buying a licence or creating an account, and whether their answer, or their silence, is recorded with a date.
8. Does it chase, and does it know when silence works for you?
Submissions go quiet. Ask how the tool shows ageing variations, and whether it knows the NEC4 subcontract’s quotation clock: four weeks for the Contractor to reply under clause 62.3, then a notification of the failure, then a further three weeks after which the quotation is treated as accepted under clause 62.6. The guide to NEC4 compensation events sets out the sequence.
The business
9. Can it produce the evidence, and can you take your data away?
If a variation ends in adjudication, you need the record in a form an adjudicator can read: the instruction, the photographs, the notices and an audit trail of who did what and when. Ask to see the export for one variation. And ask how you take everything out, in a format you can open, if you ever leave.
10. What does it cost, all in, and for how long?
Ask for the published price, whether it is per user (which quietly discourages the site team from using it), the minimum term, and what implementation or onboarding costs on top. A tool the site team is not on captures nothing.
How VariationFlow answers them
Since we wrote the questions, here are our answers. The contract and payment clocks are on the VariationFlow plan; capture on site, the register, the audit trail and the evidence pack are on the free plan too. The NEC4 periods are the subcontract’s by default, and a project’s Z clause bar can be recorded and replaces the form’s. Construction Act dates are counted under section 116, by the region where the site is, with Northern Ireland counted under its own rules. Payment dates are worked out for the payee, and a JCT project gives no pay less verdict until its own payment periods are recorded. Variations are captured on site in about a minute, with or without signal, in the crew’s own language, and go to the main contractor with a review link that needs no account. Submissions are marked as they age, the register and valuations export as CSV, and a dispute gets an audit PDF and an evidence pack. Pricing is on the pricing page, with unlimited users on the subcontractor plans. See variation management for the detail.
Common questions
What should I look for in NEC4 variation management software?
Check that it uses the NEC4 subcontract’s periods rather than the main contract’s (seven weeks to notify a compensation event under clause 61.3, not eight), that your project’s Z clause can shorten them, and that it tracks the quotation clock under clauses 62.3 and 62.6, including when the Contractor’s silence turns a quotation into an accepted one.
What should JCT variation software do for a subcontractor?
Use your sub-contract’s own payment periods rather than the main contract’s, count Construction Act days under section 116 with weekends included, and tell you as the payee when a pay less notice arrived too late. It should also get each variation instruction recorded in writing, with the main contractor’s answer and its date.
Is variation management software worth it for a small subcontractor?
It depends on how variations start. With one or two jobs and a QS who logs every change the same day, a spreadsheet can cope. Software earns its place when changes start on site, several jobs run at once, and a missed notice under the contract costs the entitlement.
This article is general information, not legal advice. The periods that apply to a job are the ones in your own subcontract and its amendments.
Hold us to the same ten questions
Free for your first job, no card: capture on site, the register and the evidence pack. The NEC4, JCT and Construction Act clocks are on the VariationFlow plan.
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