Invitation to Tender (ITT): the complete UK guide

Why emailing the NHS or a council won’t win you a contract

For years I sat on the buyer’s side of the desk, and almost every week a supplier emailed me a proposal. Many were good products. Almost none could ever become a contract.

That is not because buyers don’t care. Public bodies spend taxpayers’ money, so public sector procurement rules require them to advertise opportunities above set values, treat suppliers equally and choose using criteria they publish in advance. A buyer who signs a contract because a good email landed in their inbox can be challenged in court.

Smaller purchases below the advertising thresholds can still go through quotes or approved supplier lists under each organisation’s own rules. But for most government tenders worth winning, the route in is the same: find the published Invitation to Tender, qualify, and bid.

How the ITT process works

Every public tender follows the same broad journey, from the day the notice goes live to the day the contract is signed.

1. 1
   Tender noticeThe buyer publishes the opportunity, usually on Find a Tender.
2. 2
   RegisterYou register and download the ITT from the buyer’s portal.
3. 3
   ClarifyAsk questions before the clarification deadline.
4. 4
   SubmitUpload your tender before the deadline. Late bids are normally rejected.
5. 5
   EvaluateBids are scored against the published criteria.
6. 6
   AwardEvery bidder gets an assessment summary of their scores.
7. 7
   StandstillAt least 8 working days, then the contract is signed.

Under the Procurement Act 2023 there are two main routes. The open procedure is a single stage: anyone can bid. The competitive flexible procedure lets the buyer design stages, often a selection stage first, then an invitation to tender for shortlisted suppliers, sometimes with negotiation.

What’s inside an ITT document

An ITT document, sometimes called the ITT pack or tender documents, is often 50 to 150 pages across several files. These are the parts that matter, and the two with a yellow tag are where most bids are won or lost.

ITT qualification criteria: the pass/fail checks that knock suppliers out

From the buyer’s side, the saddest bids were the well-written ones that failed a basic rule on page one of the scoring. These are the pass fail criteria to check before you spend a single hour writing.

• 01
  Minimum turnoverOften set at around twice the annual contract value. A £150k-a-year contract may need £300k turnover.
• 02
  Insurance levelsPublic liability, employer’s liability and professional indemnity, often £5m or £10m. You may need the cover in place, or a letter promising it, at award.
• 03
  Accreditations and registrationsISO 9001, Cyber Essentials, Constructionline or CHAS, CQC registration for care, SIA Approved Contractor status for security.
• 04
  Relevant experienceUsually two or three similar contracts in recent years, with references the buyer can call.
• 05
  Exclusion grounds and declarationsCertain convictions, unpaid tax or serious past failures can exclude a supplier outright.

SQ vs ITT: and how an ITT differs from an RFQ, RFP or EOI

Buyers use several documents that look alike. This is what each one asks for.

Selection Questionnaire vs ITT, in one line: the SQ asks “are you suitable?”, the ITT asks “how will you deliver, and for how much?”. Under the Procurement Act 2023, suitability is assessed against conditions of participation, and much of your basic company information now sits on the Central Digital Platform instead of being retyped for every SQ.

Read the full SQ vs ITT guide →

ITTs under the Procurement Act 2023

The Procurement Act 2023 replaced the old rules for new procurements from 24 February 2025. Many guides online still describe the old system. Here’s what changed for suppliers.

Scotland has its own procurement rules and publishes on Public Contracts Scotland. Procurements already running before February 2025 continue under the old regulations until they finish.

Read our Procurement Act 2023 guide for suppliers →

Where to find Invitations to Tender in the UK

ITTs are published across several official portals, and buyers then run the tender itself on their own e-tendering system.

Many contracts are also awarded through frameworks: pre-approved supplier lists that buyers order from. Getting onto the right framework when it opens can matter as much as any single ITT.

Go / No-Go: should you bid for this ITT?

A strong bid can take days. Experienced bid teams run a quick Go / No-Go decision first. Ask these five questions, in this order:

1. Do we pass every pass/fail rule? If not, stop. No answer can make up for it.
2. Can we deliver the specification in that area, at that scale, from day one?
3. Is there time to write a high-quality answer before the deadline?
4. Is the value worth the effort, and can we price it to make a profit?
5. Do we know the incumbent? A re-tender with a well-liked current supplier is harder to win.

tenderITT answers the first question for you on every ITT, so your team spends its time on the bids worth writing.

How to respond to an ITT and score well

What evaluators wish every supplier knew:

• Answer the question asked, in the order it’s asked. Evaluators score against a checklist, not a story.
• Mirror the scoring criteria. If a top score needs evidence of “continuous improvement”, use those words and show it.
• Prove it with facts: numbers, named examples, response times and outcomes.
• Respect word limits and formats. Text over the limit is often not read.
• Ask clarification questions early. Answers are shared with all bidders, and they can reveal what matters to the buyer.
• Price exactly as the template asks, and check your arithmetic.
• Submit a day early. Portals slow down near deadlines, and late tenders are normally rejected.
• Read your assessment summary win or lose. It shows exactly where marks were lost.