The corrigendum that re-issues everything
Some issuing authorities publish a corrigendum as a short list of amendments. Many publish the entire tender document again with the changes made in place. The bid team now has two 180-page PDFs and a deadline. The changes may be a moved submission date, a relaxed eligibility criterion that lets in a new competitor, or a tightened technical specification that rules you out.
The usual response is to split the document between three people and ask each to read their section against the old one. That works until someone's section is the one with the change and they are reading it at eleven at night.
A worked example
Say the original tender asks for average annual turnover of a stated amount over the last three financial years, and the corrigendum changes "three" to "five". Nothing else in the paragraph moves. On page 23 of 180, inside a table of qualification criteria, that is a one-word change that can disqualify a younger company outright.
Say the same corrigendum also adds a line to the technical specification requiring a particular test certificate, and extends the bid due date by a week. The date is announced on the portal and everyone notices it. The other two changes are not announced anywhere except in the document itself.
Run the original and the corrigendum through a comparison and all three come back as separate entries, each with its page number in both versions and the old and new text. The date change is the one you already knew about. The other two are why you ran it.
What the comparison shows
Upload the original tender as the older version and the corrigendum as the newer one. The change list shows each altered sentence with its page number in both versions. Repeated headers, footers and page numbers are excluded, so a new corrigendum number printed in the footer of every page is not reported 180 times. Tables that did not change are held out; tables that changed show only the changed cells. Sections that were moved rather than rewritten are reported as moves.
The list is usually short, and it is complete for the text of the document. A typical re-issued tender produces a page or two of changes rather than a re-read of the whole thing.
Common mistakes on the bid side
- Comparing every corrigendum against the original instead of against the previous version. If corrigendum 2 adds a clause and corrigendum 3 removes it, comparing 3 against the original shows nothing, and you never learn it was there. Compare each version against the one before it.
- Trusting the corrigendum's own summary. A cover note listing the amendments is useful, but it is written by a person. Check the change list against it.
- Skipping the annexures. Forms, price schedules and draft contract terms are often re-issued alongside the main document and changed with less ceremony.
- Comparing a scanned copy with no text layer. A pure image scan is refused. If the authority published a scan, look for a digitally generated version on the portal first, or run OCR.
When the timetable is tight
Corrigenda often land a few days before the bid is due, sometimes with an extension and sometimes without. The comparison takes seconds, so the useful habit is to run it the moment a new version is downloaded and send the change list to whoever owns each affected section. The technical lead gets the specification changes, the commercial lead gets the pricing schedule and contract changes, and nobody has to re-read the parts that did not move.
Documents over 30 pages need an account or a plan. A 180-page tender is over the 100-page limit of the web plans, so either split it into volumes and compare each pair, or use an API key, which takes up to 300 pages per document.
After award
The same check is worth running once more at the end. Compare the contract the buyer sends for signature against the draft contract issued with the tender, and against any clarifications you agreed. A changed liquidated damages rate or payment term in the final contract is much easier to raise before signing than after. The guide to comparing contract versions goes through that step in more detail.
Attach the redlined PDF to the bid file as the record of what was reviewed and when.
Using it on the issuing side
Authorities can run the same comparison before publishing a corrigendum, to confirm that only the intended sections changed, and publish the change list alongside the revised document. Bidders then get the same list everyone else gets, rather than each producing their own. It is a cheap way to make sure a drafting slip in the re-issued document is caught before bidders find it.
Procurement teams in larger organisations can wire the comparison into their e-tendering workflow through the REST API, so every re-issued document is compared automatically against its predecessor. The procurement industry page covers deployment options, including running the engine inside your own network.
Try it on your own documents. Upload two versions on the homepage. Documents up to 30 pages need no account, and nothing is stored.
Industry page: PDF comparison for procurement teams