Back-to-back does not mean copy and paste: getting construction subcontracts properly aligned 

On most construction projects, the contractor will take on obligations to the employer that need to be reflected in the subcontracts below it. That is where back-to-back drafting commonly comes in. 

The difficulty is that the same wording does not always produce the same result. A notice period that works in the main contract may leave the contractor with no time to pass a claim upstream. A design requirement buried in a technical document may impose a higher standard than the subcontractor expected. A payment or dispute provision may not work at subcontract level at all. 

That is why back-to-back drafting is not simply a matter of copying clauses from one contract into another. The real task is to make sure the two contracts work together, so that obligations, rights and procedures connect properly through the contractual chain. 

Saying it is back-to-back does not make it so

“Back-to-back” is often used as shorthand for a much wider exercise involving scope, design responsibility, notices, payment, liability, insurance, termination and dispute procedures. But those provisions do not automatically line up simply because the subcontract adopts that label. Each has to be considered in the context of the subcontract itself and, where necessary, adapted so that it produces the intended result. 

Two English cases make the point well. In Cegelec Projects Ltd v Pirelli Construction Co Ltd, the subcontract contained provisions incorporating the main contract, but it also contained its own dispute resolution procedure. The court held that the main contract’s separate dispute machinery had not been carried across. The incorporation provisions were concerned principally with the execution and completion of the subcontract works and did not displace the procedure expressly agreed in the subcontract. 

The position was different in Campbell v Conoco (UK) Ltd. There, the subcontract expressly said that the main contract was accepted on a back-to-back basis and explained how references to the parties were to be read at subcontract level. The relevant main contract terms were treated as incorporated. The point is that the court has to work from the drafting actually used. Calling an arrangement back-to-back does not resolve what has been incorporated, how an upstream provision is meant to operate between different parties, or what happens where the subcontract contains its own provision on the same subject. 

Copying the whole main contract creates its own problems 

One approach is to incorporate large parts of the main contract, adapting the party names and terminology as necessary. Another is to draft a standalone subcontract intended to produce the corresponding result. The first approach may feel quicker and safer. However, it can also import clauses that were never written for a subcontract relationship, leaving genuine doubt over which references have actually been updated, and creating the risk that copied wording conflicts with a clause drafted specifically for the subcontract. A subcontract built this way can look thorough while being problematic and harder to rely on than one built for the subcontract relationship from the start. 

Matching notice periods can defeat the whole point

Giving the subcontractor the same notice period the contractor has under the main contract looks like sound back-to-back drafting. It often is not. If the main contract gives the contractor seven days to notify the employer of a delay, giving the subcontractor the same seven days can mean the contractor only finds out about the delay on the day its own deadline to the employer runs out, with no time left to act on it. That may mean giving the subcontractor a shorter window than the main contract allows, not an identical one. Matching the numbers exactly can be precisely what stops the two contracts working together as intended. 

Design wording can impose a higher standard than expected

There is a real difference between an obligation to exercise reasonable skill and care and an obligation to achieve a particular performance standard, and that difference may not appear in the main design clause. In MT Højgaard v E.ON, concerning offshore wind turbine foundations, technical requirements included a 20-year design life. The contractor had complied with the relevant industry standard and had not been found negligent, but the Supreme Court nevertheless held that the 20-year requirement was contractually effective. 

The case is a useful warning that obligations contained in an employer’s requirements document, technical specification or other contract document can impose a more demanding standard than might be apparent from the principal design provisions. If equivalent wording is being carried into a subcontract, it is important to understand both the obligation being assumed and whether the subcontractor’s professional indemnity insurance is capable of responding to it. 

Payment terms cannot simply be lifted across

Where the subcontract falls within the Housing Grants, Construction and Regeneration Act 1996, payment cannot generally be made conditional on the contractor first being paid by the employer. Pay-when-paid clauses of that kind have been ineffective under construction legislation for years, with only a narrow exception where the relevant upstream party is insolvent within the statutory provisions. For public procurement within the Procurement Act 2023 regime, which came into force on 24th February 2025, there is now another constraint. The Act implies payment terms into many public subcontracts, generally requiring sums due to be paid within 30 days of the invoice or, if later, when payment falls due, and contractual wording cannot simply override those statutory terms. Payment is one area where the subcontract has to operate within a legal framework rather than attempt to contract around it. 

Liability provisions need to match the exposure

A subcontract can contain exactly the right obligation and still leave a serious gap if liability limitshave not been checked against the money actually involved. A contractor carrying £10 million of relevant exposure upstream but relying on a specialist subcontractor with a £1 million aggregate liability cap will be left with a substantial recovery gap. Conversely, uncapped liability on a package worth a few hundred thousand pounds may expose the subcontractor to losses far beyond the value of the package and, potentially, beyond the cover available under its insurance. Caps, exclusions, indemnities, insurance, bonds and parent company guarantees need to be looked at together, against the value and risk of the package, rather than agreed clause by clause in isolation. 

Variations, termination and disputes need to work together too

Even with the obligations and liability aligned, the administrative parts of the contracts can still fail to match up. Can a contractor instruct a subcontractor to deal with a change quickly enough to meet its own deadline upstream? Can a subcontractor recover extra time or money where the contractor has no matching right against the employer? Termination and dispute processes raise the same issue, because rights at main contract and subcontract level do not move in step unless someone has deliberately made them do so. Where the subcontract is a construction contract within the Housing Grants, Construction and Regeneration Act 1996, either party also has a statutory right to refer a dispute to adjudication, and if the contractual procedure does not meet the Act’s requirements, the Scheme for Construction Contracts applies instead. 

Checking the contractual chain

The useful exercise is to take each significant obligation under the main contract and follow it through the subcontract. What obligation has the subcontractor actually accepted? Does the contractor receive notice early enough to protect its position upstream? Do the payment, variation and extension-of-time provisions produce compatible results? What liability follows if the obligation is breached, and is that liability supported by insurance or other security? 

The answers will not always require identical wording. In some cases, as with notice periods, identical wording may create the very gap the drafting is intended to avoid. 

A back-to-back subcontract therefore needs more than a general incorporation clause or a set of provisions copied from the main contract. It needs to be drafted so that the two contracts operate together when the project is live and, particularly, when something goes wrong.