Option B: Priced contract with Bill of Quantities | NEC Clauses Explained

Reviewed by LazyQS Editorial·Last reviewed: 2026-02-19

Plain English Explanation

Option B is a re-measurable contract — the work is priced against a Bill of Quantities (BoQ) with rates and prices, and the contract sum is adjusted based on the actual quantities of work executed. If you do more work than the BoQ anticipated, you are paid more; if you do less, you are paid less.

The BoQ sets out items of work with estimated quantities and your agreed rates. At each interim payment, actual quantities are measured and valued at those rates. This gives the Client less price certainty than Option A but provides a more accurate reflection of actual work done. Option B is common on civils and infrastructure projects where quantities cannot be precisely defined at tender.

Option B still allows for compensation events — scope changes, Client-caused delays, and the other 60.1 events are dealt with through the CE mechanism.

Key Takeaway

Agree and sign off interim measurements regularly throughout the project — leaving re-measurement to the end creates end-of-project disputes that are expensive and slow to resolve.

What This Means for Subcontractors

Under Option B, your payment tracks actual work done at agreed rates. Cashflow is generally better than Option A because you are not waiting for an activity to be complete. However, rate disputes can arise — particularly where the character of the work differs from what was anticipated when the BoQ was priced. Monitor measurements carefully and agree them regularly to avoid end-of-project disputes.

Common Risks & Disputes

1Quantity disputes at interim valuation, particularly for complex or hard-to-measure items
2Rates becoming inadequate if the character of the work changes substantially (different ground conditions, different access, etc.)
3BoQ errors at tender — incorrect quantities that distort the contract sum
4Omissions from the BoQ not being identified at tender and then becoming contentious at completion
5The re-measurement process falling behind programme, leading to delayed payment