Head Contracts and Subcontracts: Why Misalignment Is So Expensive

If you're a head contractor, you're sitting between two contracts: the head contract with the principal above you, and a series of subcontracts with the trades below you. Your financial exposure is determined by how well those two layers of contracts align.

When they don't align, the head contractor absorbs the difference.

The flow-down principle

The purpose of flow-down clauses in subcontracts is to pass relevant head contract obligations down to the subcontractors who are responsible for delivering that part of the work. A subcontractor performing structural concrete shouldn't be on different programme terms, different variation processes, or different notification requirements than the head contract requires.

When obligations flow down properly, a delay caused by a subcontractor creates an EOT claim at the subcontract level that mirrors the EOT at the head contract level. A variation instructed by the principal flows to the relevant subcontractor at the same scope and rate. Risk is allocated to the party responsible for it.

When they don't flow down, the head contractor is exposed at both ends — liable to the principal under the head contract for obligations they can't enforce on the subcontractor below.

Where misalignments typically occur

Programme obligations. The head contract might require weekly programme updates, a revised programme within 5 days of a delay event, and specific milestone dates. If the subcontracts don't include the same milestones and the same notification requirements, the head contractor can't enforce compliance — and can't use the subcontract as a tool to manage the programme.

Variation process and pricing. If the head contract requires variations to be instructed in writing before work proceeds, but the subcontracts allow verbal instructions, the head contractor's discipline on the head contract side won't be reflected in the subcontractor's behaviour. Verbal variations to subcontractors become claims at the head contract level.

Liquidated damages. This is the one that hurts most. If the head contract exposes the head contractor to $5,000 per day in LDs for a delay caused by a specific subcontractor, and the subcontract for that trade doesn't include equivalent LD provisions, the head contractor absorbs the LDs personally.

Insurance. Head contract insurance requirements that aren't replicated in subcontracts leave gaps in coverage. When an incident occurs and the insurance position is reviewed, gaps become disputes.

Payment terms. The Security of Payment Act applies to subcontracts as well as head contracts, but the payment terms in the subcontract — payment schedules, dispute processes, payment claim requirements — need to be consistent with the head contract cash flow to avoid being caught short.

A practical review process

Before executing a subcontract, compare it against the head contract on five dimensions:

Programme milestones and notification requirements
Variation process and pricing mechanism
LD provisions and delay liability
Insurance requirements
Payment terms and adjudication process

This review doesn't need to be a legal exercise. It needs to be a commercial one — identifying where the subcontract terms create a gap relative to the head contract obligations, and deciding whether that gap is acceptable or needs to be closed.

For complex or high-value subcontracts, a brief legal review is worthwhile. For standard trade packages, a structured commercial review by an experienced PM achieves most of the same outcome at a fraction of the cost.

Contract alignment review is available as part of our project oversight service or as a standalone engagement. Contact us to discuss your current contracts.