Specification
The detailed description of goods, services, or works required under a contract; defines what bidders must deliver.
Definition
A specification is the detailed description of the goods, services, or works required under a contract. The specification defines what the supplier is bidding to deliver and forms the contractual baseline for performance evaluation. Specifications come in several shapes: input specifications (defining specific products or methods), output specifications (defining outcomes the supplier must achieve), and hybrid specifications. Modern UK public procurement favours output specifications because they leave the supplier freedom to innovate on method while making clear what success looks like.
How it works in practice
The specification typically sits inside the Invitation to Tender pack and is the single most important document for shaping the bid response. Input specifications describe what to deliver (specific model of equipment, specific staff qualifications, specific software platform); they are typical for commodity goods and works contracts. Output specifications describe what to achieve (response times, availability levels, customer satisfaction scores, social value outcomes); they are typical for services contracts under PA 2023 which encourages output-led specification. Hybrid specifications mix both (an output specification for the service backed by minimum input standards for staff qualifications and certifications). Bidders should read the specification carefully and flag any ambiguities through clarification questions during the response window. The most common failure mode is the bidder reading what they want to see rather than what is actually written: a generous read of the specification often produces a bid that misses the buyer's actual requirement. Where the specification is unclear or appears to contain errors, raise a clarification: the buyer either confirms the intent or issues a correction, and bidders cannot subsequently rely on their own interpretation. The specification becomes the contractual scope on award; deviations during delivery are governed by the change-control mechanism in the contract terms.
Common questions
What is the difference between input and output specifications?
Input specifications describe what to deliver (specific products, staff qualifications, methods). Output specifications describe what to achieve (response times, availability, customer satisfaction). Modern UK public procurement favours output specifications because they leave the supplier freedom to innovate on method while making clear what success looks like.
What if the specification is unclear?
Raise a clarification question through the tender portal during the response window. The buyer either confirms the intent or issues a correction shared with all bidders. Do not bid on your own interpretation: if your read differs from the buyer's, you may lose the bid or win an unworkable contract.
Can the specification change during the procurement?
Minor clarifications are routine and are issued as bidder Q&A through the portal. Material changes (changes to scope, volume, location) require re-publication of the contract notice and a fresh response window. Material changes after bid submission without re-publication would be grounds for procurement challenge.