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- Completing a bill of quantities (BoQ) correctly means stating every required item in full and with the required price. Gaps or unauthorised changes lead to exclusion.
- The contracting authority usually supplies the BoQ as a GAEB file (D83/X83, “request for tender”); the bidder returns it as D84/X84 (“tender submission”).
- Missing prices, even a single “€0.00” from mixed calculation, are a mandatory ground for exclusion (VK Baden-Württemberg, 1 VK 12/21).
- Unclear items are clarified through a bidder question, not by deleting or rewriting them in the BoQ.
- Anyone who tenders regularly loses most time repeatedly filling in identical fields, which is exactly where AI-assisted completion comes in.
A Completing the bill of quantities sounds like grunt work, until a formally clean bid is eliminated from the evaluation because of a single missing price. With public contract volume of €135.2 billion in Germany in 2024 alone (Federal Statistical Office), it is often not the best bid that wins but the complete one. This guide shows bidders step by step how to fill in a BoQ correctly and in an exclusion-proof way, and where the typical pitfalls lie.
What a Bill of Quantities Is, and Why Completing It Is So Delicate
The bill of quantities is the core of the procurement documents. It breaks the tendered work down into individual items, each with an item number, short and long text, quantity (the “preliminary quantity”) and unit. The bidder enters a unit price for each item; quantity × unit price gives the total for the item, and the sum of all items gives the bid total.
For construction works, the BoQ almost always comes in GAEB format. The contracting authority sends it as a request for tender (formats D83, P83 or X83), and the bidder returns its priced bid as a tender submission (D84, P84 or X84). This separation is not a detail: anyone who edits the X83 in an arbitrary program and changes the structure risks producing a file the contracting authority cannot read in cleanly (source: gaeb-online.de).
Completion becomes delicate because the legal framework allows no leniency. The contracting authority must describe the work clearly and exhaustively under § 7 VOB/A, and in return the bidder must offer exactly what is required, without omission and without change. Two figures, a typo, an overlooked item: any of these can sink an otherwise competitive bid.
Completing a Bill of Quantities: The 6 Steps
A reliable process for bidders, from the file to submission:
- Review the procurement documents in full. Before a single figure is entered: which items are base items, which are optional or alternative items? Are there preliminary remarks that change the calculation? This review belongs in the go/no-go assessment before the actual bid work begins.
- Open the GAEB file correctly. Edit the D83/X83 only with a program that writes the GAEB format cleanly, and fill in only the intended price fields. Structure, quantities and texts remain untouched.
- Understand item types. Base items are always priced and evaluated. Optional, alternative and supplementary items follow their own rules (see next section); this is where most silent errors happen.
- Calculate every item with a unit price. Every required price must be stated in full and at the actual amount (§ 13 EU para. 1 no. 3 VOB/A). No lump-sum prices, no “€0.00” referring to another item.
- Clarify unclear items through a bidder question. If an item is contradictory or incomplete, it is not corrected unilaterally but addressed to the contracting authority via a bidder question This protects against the exclusion ground of “alteration of the procurement documents”.
- Check completeness and formalities. Before submission: is every item priced? Are all required annexes and proofs attached? Missing documents can under certain circumstances be requested later, but missing prices generally cannot (more in the article on requests for missing documents and deadlines).
Handling Item Types Correctly
Not every item is treated the same. Anyone who confuses the types calculates wrongly or creates gaps:
| Item type | Meaning | For the bidder |
|---|---|---|
| Base/standard item | Fixed component of the work | Always price it; it counts towards the evaluation |
| Optional/contingent item | Only commissioned if needed | Price it if required; permissible only in exceptional cases |
| Alternative/optional item | Alternative to the base item, contracting authority chooses | Price it, but separately from the base item |
| Supplementary item | Surcharge on another item | Calculate only the surcharge, not the entire work |
The line between optional and alternative items is blurry in practice. Case law requires the contracting authority to commit clearly (VK Bund, decision of 23.02.2017 – VK 1-11/17). For the bidder this means: if the item type remains unclear, that is a classic case for a bidder question, not a reason to guess (source: Vergabeblog).
The Most Common Errors When Completing a Bill of Quantities and What They Cost
Missing or incomplete prices. The most expensive error. Under § 13 EU para. 1 no. 3 VOB/A every required price must be stated in full; if a price is missing, the bid must be excluded under § 16a EU para. 2 VOB/A. The Baden-Württemberg Public Procurement Tribunal confirmed this: a bidder had entered “€0.00” for several items and referred to the total price, an impermissible mixed calculation that makes the bid incomparable and leads to exclusion (VK Baden-Württemberg, decision of 19.04.2021 – 1 VK 12/21; source: Update Vergaberecht).
Changes to the procurement documents. Anyone who overwrites quantities, deletes items, rewords texts or adds their own conditions alters the procurement documents, a ground for exclusion under § 16 EU para. 1 no. 1 lit. b in conjunction with § 13 EU para. 1 no. 5 VOB/A. More recent case law increasingly tests such exclusions against the standard of proportionality (including VK Bund, decision of 04.01.2023 – VK 1-105/22), but nobody should rely on that. Only the unchanged BoQ is safe.
Speculative pricing and mixed calculation. Artificially shifting prices onto individual items, for example to profit from an expected increase in quantities, is open to challenge and can be treated as impermissible mixed calculation. Cleanly calculated unit prices are not only compliant but also robust in the variation-order phase.
Overlooked annexes and proofs. A fully priced BoQ is of little use if a required data sheet or self-declaration is missing. What may be requested later and what may not is decided by the contracting authority within the scope of § 16a VOB/A; prices almost never belong to it.
Do you fill in the same items from scratch in every tender? In a short conversation we will show you how recurring BoQ fields can be filled in automatically from your own bid and reference knowledge.
How AI Speeds Up Recurring Bills of Quantities
The real time sink is rarely the calculation of a single price; it is the repetition. A metalworking company that handles 40 similar bills of quantities a year enters largely the same details in each: material properties, references, standard items, self-declarations. Manually, that means copy-paste from old bids every time, with the risk of carrying over an outdated reference.
This is exactly where AI-assisted completion replaces manual steps. Instead of maintaining templates that nobody keeps up to date, aiconver indexes a company’s existing knowledge (previous bids, data sheets, reference projects) and uses it to fill in recurring items. For aiconver customers, this reduces the effort for recurring tender fields by 80 to 90 percent (aiconver internal figure). The bidder reviews and approves instead of entering every field by hand.
The industry focus is decisive: a bill of quantities in mechanical engineering is structured differently from one in landscaping or for a leasing framework agreement. aiconver trains models per industry instead of applying a single universal model across all trades. And because public tenders contain sensitive calculation data, processing is GDPR-compliant and runs on German infrastructure, with no detour via systems outside the EU.
FAQ
Do I have to fill in every item in the bill of quantities?
Yes. Under § 13 EU para. 1 no. 3 VOB/A, every required price must be stated in full and at the actual amount. If a required item is left without a price, the bid must generally be excluded. Exceptions apply only if the contracting authority has expressly marked an item as non-binding.
What happens if prices are missing?
Under § 16a EU para. 2 VOB/A, missing prices in principle lead to mandatory exclusion. Even a “€0.00” referring to a total price counts as impermissible mixed calculation and is treated like a missing entry (VK Baden-Württemberg, 1 VK 12/21). Unlike missing documents, missing prices practically cannot be requested later.
May I change the bill of quantities or delete items?
No. Changes to the procurement documents (overwriting quantities, rewording texts, deleting items, adding your own conditions) are a ground for exclusion under § 16 EU in conjunction with § 13 EU para. 1 no. 5 VOB/A. Ambiguities are clarified through a bidder question, not by unilateral correction in the BoQ.
How do I open a GAEB file (D83/X84)?
The file supplied by the contracting authority is a request for tender (D83/X83). It is opened with a GAEB-capable program, filled in only in the price fields and returned as a tender submission (D84/X84). The structure of the file must not be changed in the process.
How long does it take to complete a bill of quantities?
That depends on the scope, from one hour for short BoQs to several days for complex construction works with hundreds of items. The biggest lever lies in recurring tenders: anyone who automatically fills identical items from their own knowledge base considerably shortens the effort.
Conclusion
A Completing the bill of quantities is not a mere formality but the point at which bids most often fail, not on price but on completeness and adherence to form. The three reliable rules: price every required item in full, never alter the procurement documents unilaterally, and clarify ambiguities through a bidder question rather than guessing. Anyone who tenders regularly gains most by automating the repetition: having standard items, references and proofs filled in from their own knowledge reduces both the effort and the risk of errors when completing the bill of quantities.
Book a free AI consultation and see, using one of your recent bills of quantities, which items can be filled in automatically.