Documents and notices
Invitation to tender(ITT)
Written by Justin Cesman, CEO of Skim. Last reviewed:
- Definition
- An invitation to tender (ITT) is the formal document package a public sector buyer issues to invite suppliers to submit a tender for a specific contract. An ITT sets out the specification, evaluation criteria and weightings, terms and conditions, pricing schedule, and submission instructions and deadline.
Key takeaways
- An invitation to tender (ITT) is the buyer's full bidding pack: specification, evaluation criteria and weightings, terms and conditions, pricing schedule, and submission instructions and deadline.
- The evaluation criteria and weightings are the most load-bearing part of any ITT — they tell you exactly what the buyer will reward, so a 70% quality / 30% price split calls for a quality-led bid, not a price race.
- An ITT differs from an RFP: an ITT is used when the buyer has already defined the requirement and wants comparable priced bids; an RFP invites suppliers to propose the solution itself.
- Under the Procurement Act 2023 the statutory terms are tender notice and associated tender documents; in the open procedure, the tender notice is the invitation to tender.
- In a two-stage procedure, suppliers pass the selection questionnaire stage before they reach the ITT; in the open procedure, selection and tender happen together in one submission.
- An ITT is legally an invitation to treat, not an offer — your submitted tender is the offer — but its stated rules can bind the buyer to follow the published process and criteria.
How it works
An invitation to tender is the core bidding document in any procurement. It tells you what the buyer wants, how they will evaluate your response, what terms you are agreeing to, and when your bid is due. A typical ITT contains several components: the specification or statement of requirements (what they want), the evaluation criteria and weightings (how they will score you), the terms and conditions (the legal framework), pricing schedules (how to present your costs in a directly comparable format), and submission instructions (format, deadline, portal). Everything needed to make a bid/no-bid decision and write a winning response is — or should be — in the ITT.
Reading the ITT carefully, truly carefully, is where experienced bidders separate themselves. The evaluation criteria and their weightings tell you exactly what the buyer values most. If quality is weighted 70% and price 30%, your bid should be a quality-led response, not a race to the bottom on cost. Missing a mandatory requirement or a submission instruction can disqualify an otherwise strong bid before it is scored on merit.
Where the ITT sits in the process depends on the procedure. In a single-stage open procedure, every interested supplier responds to one document covering both suitability and the tender itself. In a two-stage procedure, the buyer first runs a selection stage — historically a selection questionnaire — to shortlist suppliers, who then receive the ITT to submit their priced, scored bids. An ITT is not the same as the notice that advertises the opportunity: the contract notice or tender notice is the public announcement, while the ITT is the detailed document pack that follows.
An ITT also differs from a request for proposal (RFP). A buyer issues an ITT when the requirement is already defined and they want comparable, priced bids against a fixed specification, with award driven largely by price and stated quality criteria. An RFP is used when the buyer wants suppliers to propose the approach or solution itself, leaving more of the scope open. UK public sector buyers predominantly run ITT-style competitions because they must publish and apply fixed award criteria.
Invitation to tender (ITT) vs request for proposal (RFP)
| Feature | Invitation to tender (ITT) | Request for proposal (RFP) |
|---|---|---|
| When it is used | Requirement already defined by the buyer | Buyer wants suppliers to define the solution |
| What the supplier submits | A priced tender against a fixed specification | A proposal setting out approach and method |
| Award emphasis | Price and stated quality criteria, scored on set weightings | Approach, innovation and fit, alongside cost |
| Specification | Detailed and prescriptive | Outcome-led and more open |
| Typical setting | UK public sector competitive tendering | Private sector and complex or novel requirements |
Under the Procurement Act 2023
Reviewed
The bidding pack survives the reform, but the statutory vocabulary changed on 24 February 2025. The Public Contracts Regulations 2015 (PCR 2015) govern procurements that started before that date, where 'invitation to tender' was the standard term. For procurements that start on or after 24 February 2025, the Procurement Act 2023 applies and uses 'tender notice' and 'associated tender documents' as the formal terms — the tender notice announces the contract and points to the associated tender documents, which carry the specification, award criteria and assessment methodology. Both are commenced by publishing a tender notice. In the open procedure the tender notice is the invitation to tender; in the competitive flexible procedure, which replaces the old set of EU-derived procedures, the buyer designs its own stages. 'Invitation to tender' remains in everyday use, but the documents you receive under the Act will be labelled by these statutory terms.
Sources: Procurement Act 2023, section 21 (legislation.gov.uk) · GOV.UK — Guidance: Competitive tendering procedures
Why it matters for bidders
The ITT is your blueprint for winning. Misreading the evaluation criteria, missing a mandatory requirement, or misjudging the weighting between quality and price are among the most common reasons SMEs lose tenders they could have won. The discipline that separates winners is reading the ITT as a scoring rubric, not a brief: every weighting is a signal of where marks are actually awarded, and every mandatory requirement is a pass/fail gate before merit is even assessed. Paired with award data, the published award criteria become predictive — you can see how comparable contracts were scored and who won them, then build the bid the buyer is set up to reward. That approach, drawn from teams who have won £3bn+ in UK and EU public contracts, turns a 100-page document pack into a clear plan for the win.
How Skim helps
Skim's Bid Analysis agent breaks down ITT documents, surfacing evaluation criteria and weightings, mandatory requirements, and key dates — giving you a structured bid/no-bid assessment in minutes rather than the hours it takes manually. Its Opportunity Discovery agent flags tender notices across every UK and EU portal so the ITT lands on your desk with time to respond, not days before the deadline.
Frequently asked questions
- What is an invitation to tender (ITT)?
- An invitation to tender (ITT) is the formal document package a buyer issues to invite suppliers to submit a tender for a specific contract. It contains the specification, the evaluation criteria and weightings, the terms and conditions, a pricing schedule, and the submission instructions and deadline.
- What does an invitation to tender contain?
- An invitation to tender contains the specification or statement of requirements, the evaluation criteria and weightings the buyer will score against, the contract terms and conditions, a pricing schedule for presenting costs in a comparable format, and submission instructions covering the format, deadline and portal.
- What is the difference between an ITT and an RFP?
- An invitation to tender is used when the buyer has already defined the requirement and wants comparable priced bids against a fixed specification. A request for proposal is used when the buyer wants suppliers to propose the solution or approach themselves, leaving more of the scope open for the supplier to define.
- Is an invitation to tender the same as a tender notice?
- Not quite. A tender notice is the public announcement that a buyer intends to award a contract. An invitation to tender is the detailed document pack suppliers respond to. Under the Procurement Act 2023, however, in the open procedure the tender notice itself serves as the invitation to tender.
- Is an invitation to tender legally binding?
- An invitation to tender is legally an invitation to treat, not an offer, so issuing it does not oblige the buyer to accept any tender. The supplier's submitted tender is the offer. The ITT's stated rules can, however, create a process obligation requiring the buyer to follow the published procedure and award criteria.
- When do you receive an invitation to tender?
- It depends on the procedure. In a single-stage open procedure, the invitation to tender is available to every interested supplier from the start. In a two-stage procedure, suppliers first pass a selection questionnaire stage to be shortlisted, and only shortlisted suppliers then receive the ITT to submit their bids.
Sources
Related terms
Evaluation criteria
Evaluation criteria, called award criteria under the Procurement Act 2023, are the factors and weightings a buyer publishes to score tenders — covering quality, methodology, staff, price and social value — and decide the most advantageous tender. Criteria must relate to the subject-matter of the contract.
Selection questionnaire(SQ)
A selection questionnaire (SQ) is the standardised pre-qualification document under the Public Contracts Regulations 2015 that assesses whether a supplier meets the minimum standards to be invited to tender, covering exclusion grounds, financial standing and technical capability. For procurements started on or after 24 February 2025 the SQ is replaced by the Procurement Specific Questionnaire.
Bid/no-bid decision
A bid/no-bid decision is the structured assessment a supplier makes before pursuing a tender, weighing strategic fit, win probability, resource cost, commercial value, and risk to decide whether the opportunity is worth bidding for — concentrating limited bid effort on winnable, profitable work rather than chasing every notice.
Mini-competition
A mini-competition is a focused tender run among the suppliers already appointed to a multi-supplier framework agreement or dynamic market, inviting all eligible members of the relevant lot to bid for a specific call-off contract using the evaluation criteria and rules pre-set by the framework.