GAEB tendering, a digital tender route using the exchange standard of the Gemeinsamer Ausschuss Elektronik im Bauwesen, the German Joint Committee for Electronics in Construction, is not decided only in the bid comparison. It is decided when the bill of quantities is built. If quantities, item numbers, item texts and attachments are unclear, the error returns as a bidder question, a qualification or a unit price that cannot be compared.
From bill of quantities to award
A Leistungsverzeichnis, usually shortened to LV, is the German bill of quantities that describes the works by item, quantity and unit. AVA, Ausschreibung, Vergabe und Abrechnung, means tendering, award and billing; it is both the software category and the process that carries the LV from cost planning into procurement and later valuation. GAEB DA XML is the structured data exchange used for these LV records in German construction; the official GAEB data exchange FAQ describes the exchange phases.
A clean route does not start with export. It starts with testable item descriptions, complete preliminaries, unambiguous units and a stable Ordnungszahl. An Ordnungszahl, or OZ, is the unique item number in the LV. It is the reference point for bidder questions, bids, comparisons, variations and final accounting.
Before the file is sent, the LV should be reviewed inside the AVA process. Do quantities and units match? Are provisional items marked? Are alternatives described clearly? Are drawings, surveys and special contract conditions versioned? Only then does the GAEB exchange add value.
X81 to X84: which file when
The exchange phase defines which data the GAEB file contains. Four files matter most on the route from tender to award:
- X81 Leistungsbeschreibung: the performance description or LV handover, often used between designer, client and AVA system. It contains work items, but no bidder price.
- X82 Kostenanschlag: the cost estimate, meaning the LV with estimated prices. It supports internal costing and budget checks. If costs are tracked by DIN 276, the German standard for construction cost classification, the mapping should be maintained cleanly.
- X83 Angebotsaufforderung: the invitation to tender file for the bidder. It normally excludes internal cost estimates. This is the file the bidder uses for pricing.
- X84 Angebotsabgabe: the bid submission file returned by the bidder. It contains unit prices, totals and, depending on the structure, bidder text additions.
The split between X82 and X83 is important. If internal estimates are sent by mistake, the client exposes its own expectations. If the X83 is incomplete, the result is avoidable clarification or bids that do not compare cleanly.
Check returns and build the comparison
A Preisspiegel is the German bid comparison, a table that compares received bids at item, section and total level. It is not a substitute for professional evaluation. It shows where prices look unusually low, high or incomplete.
The return process starts with formal checks of the X84 files. Does the X84 match the issued X83? Has the OZ structure changed? Are unit prices missing? Have free text fields been completed? Does the bid contain qualifications, cash discounts, rebates or conditions in places that cannot be compared automatically?
Only after that should the comparison be built. AVA software can place offers next to each other item by item, flag outliers and calculate totals. It cannot make the award decision. A very low unit price may be a calculation error, a different assumption about execution or a deliberate pricing strategy. That point must be clarified where the tender procedure allows it.
A separate GAEB bid comparison file, X84P, should not be treated like the normal bidder return, X84. In practice the comparison is usually generated inside the AVA system from the X83 and the related X84 bids. If a comparison has to be exported, confirm first which format the recipient can actually process.
Common errors in GAEB exchange
Many issues are editorial rather than technical. The file may be valid while the LV is still not clear enough.
- Inconsistent units: m, m2, item and lump sum should not change by habit. The unit and quantity take-off must fit the work item.
- Missing attachments: if drawings or technical descriptions are assumed in the item text, they need to be issued with status and reference.
- Changed OZ structure: if numbering changes after the X83 has been issued, bidder questions and returns quickly drift apart.
- Mixed price types: base items, alternatives and provisional items need clear marking or the bid comparison will be distorted.
- Unclear bidder text additions: if products, makes or execution details must be inserted, the file should show what is mandatory and what is informative.
- Spreadsheet detours: spreadsheets can help review, but they can also damage structure, hierarchy or rounding. For binding exchange, the GAEB file should remain the leading record.
Data protection also matters. DSGVO, the German term for the General Data Protection Regulation, protects personal data. GAEB files mostly contain work data, but contact names, property addresses or internal notes can still be personal or confidential.
What a clean award recommendation needs
The Vergabeempfehlung, or award recommendation, is the professional reasoning for the offer that should receive the contract. It should not merely name the lowest total. It should show how the received bids led to a defensible decision.
In practice it usually includes checked bid totals, rebates, excluded or clarified qualifications, arithmetic corrections, technical issues, programme and capacity information, comparison with the cost plan and a clear recommendation. For public clients, VOB/A, the German procurement rules for construction works, shapes the tender procedure. VOB/B, the German standard terms for construction execution, matters when it is effectively incorporated into the contract. This is an orientation, not legal advice.
A simple example: Bid A is about 3 per cent below Bid B, but contains a qualification on the execution period. Bid B is slightly more expensive, confirms all dates and has no open bidder text additions. The bid comparison shows the numbers. The award recommendation explains the commercial and technical assessment that follows.
Conclusion: structure before export
Good GAEB tendering is not a file click. It is a controlled sequence: clear LV, correct exchange phase, checked X84 return and a bid comparison that receives professional judgement.
Structify supports this route in the project context: LV data, GAEB exchange, bid comparison and award records stay together. You can find more under AVA and tendering. Structify is software support and does not replace legal or professional decision-making. If you would like to see what this looks like on your project, book a short online demo.