Provisional Sums — Definition, Expenditure, and Recovery

Understanding Provisional Sums in Construction Contracts

Provisional sums are a fundamental yet often misunderstood component of construction contracts. In practice, provisional sums are allowances included within the contract sum for work that is not fully defined at the time of tender. However, a common misconception is that provisional sums represent guaranteed expenditure or secured revenue for the contractor.

This misunderstanding creates significant commercial and legal risks. Contractors frequently assume that provisional sums will be fully expended and therefore rely on them when calculating overhead recovery, pricing preliminaries, and forecasting cash flow. In reality, provisional sums are not commitments — they are merely placeholders subject to the employer’s instruction.

The Core Problem with Provisional Sums

The primary issue with provisional sums lies in the disconnect between expectation and contractual reality.

From a contractor’s perspective, the inclusion of substantial provisional sums (for example, £500,000 in a bill of quantities) may be treated as part of the anticipated turnover. This assumption often feeds into:

• Overhead recovery strategies
• Profit margin calculations
• Resource allocation and planning

However, if the employer chooses not to instruct the provisional sums, the financial consequences can be severe. The contractor not only loses the direct value of the provisional sums, but also the indirect contribution to:

• Head office overheads
• Site preliminaries
• Profit margins

This creates a hidden commercial risk that is often underestimated at tender stage.

Programming Risks Associated with Provisional Sums

Beyond cost implications, provisional sums also introduce significant programming risks.

Contractors frequently build their construction programmes around the assumption that provisional sums will be executed at specific stages. When these provisional sums are:

• Not instructed, or
• Instructed significantly later than expected

the result can be:

• Disruption to sequencing
• Inefficient resource utilization
• Delays to critical path activities

In such cases, the contractor may face difficulties in maintaining programme integrity, particularly where dependencies were built around provisional sums work.

Legal Principles Governing Provisional Sums

The legal treatment of provisional sums depends largely on whether they are classified as defined or undefined, as established under RICS guidance (NRM2) and commonly adopted in JCT contracts.

Defined Provisional Sums

Defined provisional sums are those where sufficient information is provided at tender stage to allow the contractor to:

• Make programming allowances
• Include attendance and preliminaries

In this case:

• The contractor is deemed to have allowed for the provisional sums in their programme
• If the provisional sums are not instructed, there is no automatic entitlement to recover associated preliminaries or disruption costs

Undefined Provisional Sums

Undefined provisional sums apply where insufficient information is available at tender stage.

In this scenario:

• The contractor cannot reasonably plan for the provisional sums
• When instructed, the contractor is entitled to claim:
  • Additional preliminaries
  • Programme adjustments
  • Reasonable cost impacts

This distinction is critical in determining entitlement and risk allocation.

Employer’s Rights and Limitations on Provisional Sums

Under most standard forms of contract, the employer is not obligated to instruct provisional sums. If the work is not instructed:

• The provisional sums are simply omitted
• The contract sum is reduced accordingly
• The contractor receives no payment

However, this does not grant unlimited flexibility to the employer. If provisional sums (especially defined ones) are instructed in a manner that:

• Disrupts the contractor’s programme, or
• Alters the planned sequence of works

the contractor may have valid grounds for a claim related to:

• Disruption
• Loss of productivity
• Additional cost

Practical Management of Provisional Sums

For Contractors

To manage the risks of provisional sums, contractors should:

• Avoid treating provisional sums as guaranteed income
• Clearly distinguish between defined and undefined provisional sums
• Reflect defined provisional sums realistically in the construction programme
• Include contingencies for undefined provisional sums
• Track instructions carefully and claim entitlements where applicable

For Employers

Employers should:

• Clearly define the scope of provisional sums at tender stage
• Identify whether provisional sums are defined or undefined
• Provide timely instructions for provisional sums
• Avoid late or disruptive implementation of provisional sums

Effective communication is essential to minimize disputes related to provisional sums.

Risks Associated with Provisional Sums

Contractor Risks

• Over-reliance on provisional sums for revenue
• Cash flow shortfalls if provisional sums are not instructed
• Programme disruption due to changes in provisional sums timing

Employer Risks

• Incorrect assumption of flexibility in instructing provisional sums
• Exposure to claims for disruption and delay
• Increased project cost due to inefficient timing of provisional sums

Mitigation Strategies for Provisional Sums

Effective risk mitigation for provisional sums should begin at tender stage:

• Clearly classify all provisional sums as defined or undefined
• Include explicit programming assumptions for provisional sums
• Align contractual documents with realistic construction sequencing
• Maintain early and transparent communication regarding provisional sums

During project execution:

• Monitor provisional sums instructions closely
• Assess programme impact before issuing instructions
• Maintain proper records to support or defend claims

Conclusion: Provisional Sums Are Allowances, Not Guarantees

Provisional sums are an essential procurement tool, but they must be understood correctly. They are allowances, not entitlements, and their treatment depends on contractual classification and timing of instruction.

Both contractors and employers must approach provisional sums with a clear understanding of:

• Their legal nature
• Their impact on pricing and programming
• Their role in risk allocation

Proper management of provisional sums can significantly reduce disputes, protect profitability, and ensure smoother project delivery.

Provisional Sums