What changed in addendum 3?
Diffing tender revisions, corrigenda and addenda before bid day. Classify each changed line, re-match only what moved, and keep the deviation register in step with the BOQ.
- KKK Manoj KumarCo-founder
4 min read
Addendum 3 arrives on a Thursday afternoon for a bid due Monday. It's a 40-page PDF and a revised BOQ in Excel, and the cover letter says the BOQ "has been revised as per the attached". It doesn't say which lines. Your team priced Rev 0 last week, built the compliance sheet, wrote six deviations and got the sales head to sign off the margin. Now someone has to work out what changed and what has to be redone before anyone can trust the number again.
The name differs by region and the job is the same. In Indian public tenders it's a corrigendum, often issued after the pre-bid meeting with the minutes and BOQ clarifications attached, as in this RBI tender. In the GCC it's an addendum or tender bulletin from the consultant, sometimes with a revised BOQ and sometimes with only a list of changed clauses. In the US it's an addendum to the bid documents, with revision clouds and deltas on the drawings, and the bid form asks you to acknowledge each one by number. Miss one and the bid can be ruled non-responsive, or you've priced the wrong scope.
Diff the BOQ before you read the letter
The cover letter is the consultant's summary of what they think changed. The revised BOQ is what you'll be priced against. So diff the BOQ first, line by line, against the revision you priced.
That's harder than comparing two spreadsheets cell by cell. Item numbers shift when a line is inserted. Descriptions get reworded with no change in meaning. Sections move. A diff that keys on row position will report half the BOQ as changed. Key on the item number where it's stable, fall back to section and description where it isn't, and count a line as changed only when a value that affects price or compliance has moved.
Every changed line then falls into one of five kinds, and each kind needs different work:
Addendum 3 vs Rev 0 (priced) 17 lines changed
10 quantity only 4.2.14 120 → 146 Nos re-priced
3 spec change 4.6.03 IP44 → IP65 re-matched → VS-BLK-6512-830 (91)
2 new lines 4.7.01, 4.7.02 façade linear, 24 V, RGBW, DMX
no catalogue match → review
1 deleted 4.3.09 track spot, 22 W removed from price and register
1 wording only 4.1.02 no parameter changed logged
Amount delta +₹6,42,300 · deviation register: 1 closed, 1 openedA quantity change needs a new amount and nothing else, because the match, the rate and the deviation status all still stand. A spec change needs a fresh match, because the SKU you offered may no longer comply. New lines are matched from scratch. Deleted lines come out of the price and out of every document that mentions them. A wording change is logged and left alone, unless the new wording changes a parameter, in which case it's a spec change.
Re-match only what changed
Once the lines are sorted, only spec changes and new lines go back through matching. A quantity change on a line that's already matched, reviewed and priced shouldn't reopen it. If it does, the estimator re-reviews 400 lines because 17 moved, and the addendum costs as much as the first round did.
The changed lines go through the same pipeline as the first round. Extract the attributes, filter the catalogue, score against the rubric, and abstain when nothing fits. Then they go into the same review queue, marked as addendum lines so the estimator can work them as one batch. The façade linear lines in the example may well come back with no match. On a Thursday, that's a useful answer. It tells you that you need a bought-out item or an exclusion while there are still three days to arrange one.
Watch the lines where the spec moved and your offer still complies. A change from IP44 to IP65 on a bollard you already offered at IP65 needs no new match, but the compliance sheet still quotes the old specified value. It's an easy thing to leave stale, and the evaluator reads the compliance sheet.
Keep the deviation register in step
Addenda do their quiet damage in the deviation register. Your Rev 0 offer declared that 4.6.03 deviates on IP rating. Addendum 3 changes the spec, the new SKU complies, and that deviation should close. Meanwhile a new line opens a deviation nobody has written up yet. If the register is a separate Word file, it will be out of date by Monday. GCC consultants in particular reject submittals for undeclared deviations, and a stale register is how a deviation goes undeclared.
Small parameter gaps are exactly what reviewers catch. A public addendum from the Philadelphia Parking Authority rejected a proposed fixture substitution because it offered CRI 85 against a specified CRI 90. When the spec and the offer drift apart between revisions, that's the kind of gap that slips through.
So generate the register from the line data instead of keeping it beside the BOQ. Each deviation belongs to a line and a spec clause. When a line is re-matched, its deviations are recomputed, and the diff shows which closed and which opened. The same goes for the compliance sheet, the price summary and the list of acknowledged addenda in the cover letter. All of them come from the current revision of the BOQ, and each one states which revision that is.
Before the next tender comes in, decide how you'll identify a BOQ line across revisions. Item number, section and a normalised description is enough to start. Keep every revision you priced, with its date, and record which addendum numbers you acknowledged on the bid form. When addendum 3 lands, the first thing you want is a list of the 17 lines that moved and what kind of change each one is, and that only works if Rev 0 is still there to compare against. Addendum tracking is part of our tender analysis work.