Preparing a price comparison: tenders side by side

A price comparison (Preisspiegel) lays the tenders of several bidders side by side, item by item. Preparing it has two parts. A fixed program checks the arithmetic in each tender and compares the prices. The AI reads the texts and points out anomalies, such as changed item texts, reservations and missing information. Who is assessed how, and to whom the contract is awarded, a person decides. This is not legal advice.

What a price comparison is

The GAEB describes the evaluation like this: the client evaluates the tenders received in a price comparison, at the level of unit rates and across the tender total. This holds whether the tenders arrive as GAEB files or as spreadsheets. How tender files are built is explained in the article on GAEB exchange phases.

A price comparison usually has one row per item of the bill of quantities and one column per bidder. The totals sit underneath. The GAEB technical documentation also knows a separate exchange phase for it (X84P) but lists it only in beta status. In many offices it therefore remains a spreadsheet. In building design, preparing a price comparison by individual items or part services is one of the basic services of phase 7 (Annex 10 of the HOAI, the German fee scale for architects and engineers).

The graphic shows the sequence. A fixed program does the first three steps, the AI the fourth as preparation, and a person takes the fifth.

What is checked first: the arithmetic

Before prices are compared, it must be clear that each tender is correct in itself. The VOB/A (German procurement and contract rules for construction works) names an arithmetic, technical and economic examination of the tenders (section 16c(1)). For the arithmetic it says: if the total of an item does not match the product of quantity and unit rate, the unit rate prevails. Where the award is made for a lump sum, that sum applies regardless of any individual prices stated (section 16c(2)).

These references come from part 1 of the VOB/A, 2019 edition, the part for procurements below the EU thresholds. It was last amended in section 3a (value thresholds, since 1 January 2026); the sections cited here were not affected. The new version of the VOB/A that the Federal Ministry for Housing, Urban Development and Building announced in the Federal Gazette on 24 August 2026 (2026 edition) concerns only parts 2 and 3. These cover construction procurements above the EU thresholds and construction contracts relevant to defence and security. For part 2, section 2 of the Public Procurement Ordinance (VgV) now also refers to the new version.

For the checking steps in this article, that changes little. According to the wording of the 2026 edition, part 2 still contains the same rules in substance: where the arithmetic is wrong the unit rate prevails (section 16c EU(2)), missing price entries in principle may not be requested later (section 16a EU(2)), and changes to the procurement documents are not permitted (section 13 EU(1) no. 5). What has changed is the later request for documents: the distinction between documents relating to the company and documents relating to the works falls away, but documents relating to the works still may not be corrected (section 16a EU(1)). Which part applies to your procedure depends mainly on the contract value, and your legal adviser clarifies that.

This check is pure arithmetic. A fixed program recalculates quantity times unit rate for every item, adds up over the structure and compares the result with the stated total. Deviations are listed with the item and the amount. A language model does not belong here, because it does not calculate figures reliably.

The price comparison

The comparison per item and per tender total follows. The program can show, for example:

• the range of unit rates per item and each bidder’s distance from the mean of the tenders,
• items where a bidder has entered no price,
• items where a bidder is clearly below or above all the others,
• the totals per level of the structure, so that it is visible where a difference arises.

An anomaly is not yet a finding. A very low unit rate may be a mistake, a different method of execution or a deliberate calculation. Under the VOB/A, a tender with an inappropriately high or low price must not be awarded the contract. Where a price seems inappropriately low and this cannot be judged from the available price calculation documents, the bidder must be asked in text form for an explanation (section 16d(1)). Whether a price is inappropriate is judged by no program and no AI. That is a task for the contracting authority, in the individual case with legal advice.

What the AI flags in the texts

The figures in a tender are only half of it. In the tender, the bidder supplements the bill with prices, bidder text additions and free quantities, according to the GAEB technical documentation. The project details, the bill and above all its structure are to be taken over unchanged from the invitation to tender. For tenders as spreadsheets or PDF, covering letters and annexes come on top. The language model reads these texts and sets them against the original. Typical notes:

1. An item text differs from the text of the invitation, even in a single word. Under the VOB/A, changes to the procurement documents are not permitted (section 13(1) no. 5).
2. A text addition or the covering letter contains a reservation, for example on price escalation, conditions or an assumption about quantity.
3. Information is missing that was required, for example declarations, evidence, makes of product or subcontractor details.
4. A tender names an alternative method without it being marked, on a separate annex, as an alternative tender (section 13(3)).

Each note names the source and sets the two texts against each other. That is a marker, not an assessment. Whether the change is permissible, whether a reservation makes the tender unusable and whether anything may be requested later is governed by procurement law. The VOB/A lists grounds for excluding tenders, among them tenders not received in time and tenders where declarations or evidence that the client reserved the right to request are not supplied within the deadline set (section 16(1)). Missing documents may be requested later under certain conditions. Missing price entries in principle may not be requested later, with a narrow exception only for items of minor importance (section 16a). How that applies to a particular tender is for your legal adviser or the contracting authority. The AI supplies only the source references.

The second graphic sets out the check questions in the order in which they arise in a price comparison, each with its source. It does not replace a legal check and says nothing about how a procedure turns out in the individual case.

Where the decision lies

The last stage of the graphic belongs to a person. For the evaluation the VOB/A requires that only award criteria, and where applicable their weighting, are taken into account that are named in the notice or in the procurement documents (section 16d(1) no. 5). Which criteria these are for you is set by your invitation to tender. The price comparison is a document for the evaluation and does not replace it.

Anyone who chooses between tenders as a client without a formal procurement procedure had better record the reasons in a traceable way. In the end a person has to sign, and that person answers for the choice.

Time and effort

I do not give a figure for time saved here, because I cannot substantiate one. The gain probably lies in compiling and recalculating and in going through many texts. Whether it occurs for you, measure on a completed procurement by timing compiling, checking and assessment separately.

Data and confidentiality

Tenders contain prices and the bidders’ calculation details. They belong only on a platform that can be operated in line with the GDPR, not in a consumer chat service. For tenders that arrive as scans, text recognition comes first, and its limits are shown in the article on old plans and poor scans.

What you can do now

1. Decide in which form you request tenders, ideally as a GAEB file (X84) and also as PDF, where the procedure allows it.
2. Build a price comparison template with one row per item, one column per bidder, the totals and a column for notes.
3. Record in writing beforehand which criteria your evaluation uses and how they are weighted.
4. Clarify with your legal adviser which procurement rules apply to your procedures and what you may request later.