Part 3: Award of public contracts and procedures Chapter 2: Competitive award Section 20: Competitive tendering procedures
Subsection (1) requires that before awarding a public contract under section 19 (award of public contracts following a competitive tendering procedure), a contracting authority must carry out a competitive tendering procedure in accordance with a tender notice (like an advert) and associated (supporting) tender documents. This ensures potential bidders know what to expect from the procedure.
	Subsection (2) sets out that a competitive tendering procedure can take two forms. The first is an "open procedure", which is a single stage procedure whereby the opportunity for the public contract is advertised and any interested party can submit a tender (and the authority will decide who to award the contract to solely on the basis of that single tender, in accordance with section 19). The second is a "competitive flexible procedure" which is any other competitive tendering procedure which the contracting authority considers appropriate for the purpose of awarding the public contract.  Any competitive flexible procedure designed by the contracting authority will need to operate within the bounds of the provisions of the legislation (such as the covered procurement objectives, publication of required notices and other requirements applicable to a competitive tendering procedure); but otherwise can be designed around what would work best for the specific procurement.
	Subsection (3) requires contracting authorities to ensure that the procedure is a proportionate means of awarding the contract, having regard to the nature, complexity and cost of the contract. This is to avoid procedures being designed in a manner that is unnecessarily complex or burdensome.
	Subsection (4) further differentiates the two types of competitive procedure by reference to some of the actions that could be taken in a competitive flexible procedure.  In contrast to an open procedure, a competitive flexible procedure will likely be multi-staged and therefore may (under subsection (4)(a)) limit the number of suppliers participating in a procurement (or progressing to the next stage). For example, a competitive flexible procedure may have a first stage that invites tenders from all interested parties and a second price negotiation stage with those suppliers successful at the first stage. Alternatively, the first stage could be a request to participate which outlines the essential requirements that must be met in order for suppliers to tender (the conditions of participation- see section 22), and thereafter only those suppliers who can meet those conditions are invited to bid.
	Subsection (4)(b) identifies that award criteria can be refined in the course of the procedure, within the parameters set out in section 24. Subsection (4)(c) prohibits contracting authorities from allowing participation of suppliers not previously involved and/or suppliers excluded in an earlier stage.
	Subsection (5) sets out other ways a contracting authority may remove suppliers from a competitive flexible procedure. Under subsection 5(a), if the supplier has not complied with the conditions of participation set for the procurement (pursuant to section 22) they may be excluded. Subsection 5(b) states that a supplier may be excluded when they have failed to meet any intermediate assessment of tenders. Subsection 5(c) provides that contracting authorities may also exclude a supplier that is not a United Kingdom supplier (as defined in section 90(7)) or treaty state supplier (as defined in section 89). Subsection 5(d) provides that a contracting authority may exclude a supplier that intends to sub-contract the performance of all or part of the contract to a supplier that is not a United Kingdom supplier or treaty state supplier.
	Subsection (6) explains that the reference to intermediate assessment of tenders in subsection (5)(b) means assessing which tenders satisfy the contracting authority's requirements and best satisfy the award criteria at the point of exclusion by reference to certain assessment requirements relating to award criteria (which are dealt with in section 23).
	Subsection (7) allows a competitive tendering procedure to have a limit to the number of lots any one supplier can tender for.
	Subsection (8) refers to section 27 (excluding suppliers from a competitive flexible procedure) section 28 (excluding suppliers by reference to sub-contractors) and section 30 (excluding suppliers for improper behaviour), which make provision for excluding suppliers that are excluded or excludable suppliers or that are intending to subcontract to excluded or excludable suppliers (excluded and excludable suppliers are defined in section 57 (meaning of excluded and excludable suppliers.)
	Subsection (9) refers to sections 32 (reserving contracts to supported employment providers) and 33 (reserving contracts to public service mutuals) about reserving contracts to certain suppliers.
	Subsection (10) refers to section 34 (competitive award by reference to dynamic markets), which allows the exclusion of suppliers that are not members of a dynamic market or part of a dynamic market.