Understanding provisional sums and prime cost clauses in Queensland construction contracts

Rostron Carlyle Rojas


Rostron Carlyle Rojas is an Australian firm providing accessible legal advice across business and personal law. With offices in Brisbane and Sydney and technology to serve overseas clients, they prioritize building relationships with clients.
Without these clauses, uncertainties in project scope and costs may lead to disputes, delays, and unexpected costs.
Australia Real Estate and Construction
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In the realm of construction contracts in Australia, certain clauses play pivotal roles in ensuring smooth project execution and fair allocation of costs. Two such clauses are provisional sums and prime cost clauses. While they may seem similar, understanding their nuances is crucial to avoid potential disputes and ensure clarity in contractual obligations.


Provisional sums are mechanisms used in fixed price contracts to accommodate uncertain elements of the project. They allow for the commencement of the project even when certain aspects, particularly design elements, are not finalized. These sums are adjusted based on the actual cost of performing the provisional sum work once such costs are determined.

Under Industry Standard Contracts such as the Australian Standard AS 4000-1997 General Conditions of Contract, provisional sums enable early project commencement while accounting for uncertainties. The adjustment of provisional sums is typically based on two components: the actual cost incurred by the contractor in performing the work and the applicable overheads and profit.

However, ambiguity in the description of provisional sum work can lead to disputes. It is crucial for both parties to ensure precise descriptions to mitigate potential conflicts. Principals should also clarify whether overheads and profit are included in provisional sum allowances or form part of the contractor's fixed price to avoid misunderstandings.


Similar to provisional sums, prime cost items provide allowances for specific supply items where the final choice hasn't been made at the contract's onset. Under Industry Standard Contracts, such as an AS 4000, prime cost items work in conjunction with provisional sums, often encompassing similar provisions.

Traditionally, prime cost items cover only the cost of supplying the relevant item and exclude associated work costs like installation. However, under AS 2124 and AS 4000, prime cost items are often treated similarly to provisional sums, blurring the distinction between the two.


Failure to include provisional sum and prime cost items in construction contracts can pose significant risks. Without these clauses, uncertainties in project scope and costs may lead to disputes, delays, and unexpected financial burdens on both parties. Principals may face inflated project costs, while contractors may encounter difficulties in accurately estimating their expenses, potentially affecting profitability.

In conclusion, while provisional sums and prime cost items serve similar purposes in accommodating uncertainties in construction projects, understanding their differences and legal implications under Queensland law is essential. Clarity in contractual terms, precise descriptions of work, and proactive risk management are imperative to mitigate potential disputes and ensure successful project outcomes.


The omission or poor drafting of provisional sum and prime cost clauses in construction contracts can have profound implications on the project's execution, leading to significant risks for both the principal and the contractor. Here is a more detailed exploration of the potential effects:

  1. Uncertainty and Disputes:
  • Without clearly defined provisional sum and prime cost items, there is ambiguity regarding the allocation of costs for uncertain elements of the project.
  • This ambiguity often leads to disputes between the principal and the contractor, particularly when determining whether certain work falls within the scope of provisional sums or should be covered under the fixed price.
  • Disputes arising from poorly drafted clauses can result in costly litigation, project delays, and strained relationships between the parties involved.
  1. Financial Implications:
  • Poorly drafted clauses fail to adequately account for the actual costs incurred by the contractor in performing the provisional sum work or supplying prime cost items.
  • Contractors may find themselves in a position where they bear additional costs that were not properly accounted for in the contract.
  • Principals may face unexpected increases in project costs if provisional sums are not adjusted accurately to reflect the actual expenses incurred.
  1. Project Delays and Disruptions:
  • Ambiguity in provisional sum and prime cost clauses can lead to delays in project completion as disputes over costs and scope are resolved.
  • Contractors may hesitate to proceed with work for which costs are uncertain, leading to interruptions in project progress.
  • Delays in completing the project can have cascading effects, including financial penalties for late delivery and damage to the contractor's reputation.
  1. Impact on Profitability:
  • Contractors rely on accurate cost estimations to determine their profitability on a project.
  • Poorly drafted clauses that do not adequately address provisional sums and prime cost items can erode contractor profitability due to unexpected expenses and disputes over costs.
  • Contractors may become reluctant to bid on future projects or may need to inflate their bids to account for the increased risk associated with poorly defined contractual terms.
  1. Legal and Regulatory Compliance:
  • Construction contracts are subject to various legal and regulatory requirements.
  • Omitting or inadequately addressing provisional sum and prime cost items may result in non-compliance with applicable laws and standards, exposing both parties to legal liabilities and penalties.

In summary, the omission or poor drafting of provisional sum and prime cost clauses in construction contracts can introduce uncertainty, disputes, financial risks, project delays, and legal liabilities. Clear and precise contractual terms are essential to mitigate these risks and ensure the successful execution of the project.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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