Guide · 7 min read · Updated 2026-07-25
Unpaid Variations: How Subcontractors Recover the Money They Are Owed
Ask a subcontractor where their margin went on a losing job and the honest answer is usually the same: work they did but never got paid for. Not because the claim was weak, but because it was never captured, never priced, or noticed too late to matter.
Recovering variation money is a process, not a moment of courage at final account. This guide walks through that process: finding the scope changes, pricing them properly, notifying them in a way that survives scrutiny, and escalating when the answer is no.
Step 1: Find the scope change while it is still fresh
Every variation starts as a gap between what you priced and what you are being asked to do. The only reliable way to spot that gap is to compare instructions against your tender documents: the priced bills or schedule, the drawings you tendered on, and your qualifications and exclusions.
Set a simple site habit: every revised drawing, site instruction, RFI answer and "can you just" email gets checked against the priced scope the day it arrives. On busy jobs the changes that slip through are rarely the big obvious ones. They are the tenth small change in a fortnight, each one an hour here and a visit there.
Step 2: Price it properly, not hopefully
A round-number claim is easy to reject. A priced build-up is hard to ignore. Use the valuation rules in your subcontract: measured work at bill or schedule rates where the work is similar, adjusted rates where conditions differ, and daywork records where measurement is not practical.
Daywork sheets are only worth what their signatures are worth. Get them signed while the operative and the site team both remember the day, and note on the sheet what instruction the time relates to.
Step 3: Notify it and keep it alive in every application
A variation that is not notified in time can be lost entirely if your subcontract makes notice a condition precedent. Send a short written notice when the change lands, then carry the item in every application for payment until it is paid or formally rejected. Our guide to writing a JCT variation notice covers the wording.
The Construction Act payment regime is your friend here. Once a variation sits in a payment application, the payer has to deal with it through payment notices and pay-less notices within statutory timescales. Silence has consequences for them, not just for you.
Step 4: Escalate with a decision, not a grudge
Most variation disputes settle in negotiation once the paperwork is strong, because the contractor can see how an adjudicator would read it. If negotiation stalls, adjudication under the Construction Act is designed exactly for this: either party to a construction contract can refer a dispute at any time, and the adjudicator normally decides within 28 days.
Adjudication costs real money, so size the decision like a commercial one: the value of the variations, the strength of your records, and the relationship. A well-documented £40,000 claim is a very different proposition from a poorly evidenced £4,000 one.
The golden thread: what your records need to show
- The instruction: who asked for the change, when, and in what form
- The scope gap: what the tender documents said against what was built
- The notice: when you told them, and that it was in time
- The price: rates, measures and signed daywork records behind the number
- The applications: every application that carried the item, and every response or silence
This is exactly the paper trail BuildPredict builds automatically: it reads your tender and subcontract, flags scope changes in the documents and emails you feed it, and drafts the variation notice for you.
Frequently asked questions
Is there a time limit for claiming variations?
Two limits matter. Your subcontract may set short notice periods, sometimes as a condition precedent to payment. Beyond that, contract claims are subject to statutory limitation: six years from breach for a simple contract, twelve for a deed. Practically, recovery gets much harder once the final account closes.
Is pay-when-paid legal in the UK?
Broadly no. Section 113 of the Construction Act makes pay-when-paid clauses ineffective, with one narrow exception: where the party up the chain is insolvent. Watch instead for pay-when-certified wording and long payment cycles that try to achieve a similar delay by other means.
What if I have no written instruction at all?
You still have options. Contemporaneous records, site diaries, photos, emails around the work and the fact the work exists in the building all count as evidence. Confirm verbal instructions in writing from now on, and remember that a valuation can also rest on the conduct of the parties.
How much does adjudication cost?
Typically several thousand pounds upwards once you include the adjudicator’s fees and your own time or representation, and each side usually bears its own costs. That is why strong routine records matter: most well-papered claims settle before anyone appoints an adjudicator.
This guide is general information for UK construction businesses, not legal advice. Contract terms differ, and for significant disputes or heavily amended contracts you should take professional advice.