A design deliverable
Article 22 of Annex I.7 to the public contracts code lists the bill of quantities and the quadro economico as a single entry among the documents of the progetto esecutivo. The wording is not accidental: the two deliverables are conceived as a pair, and the second is built from the first.
The reference structure is that of the costs defined in article 5 of the same annex, as amended by Legislative Decree 209 of 2024. The amendments must be read together with the original text.
The four column structure
Established professional practice sets the document out in four columns, separating amounts prior to the tender from those following it, with their respective subtotals. Separating pre-tender from post-tender amounts is what makes the discount legible.
The pre tender column is completed according to the figures deriving from the bill of quantities prepared during design. The post tender column is populated progressively according to the awards made and the costs actually incurred, including taxes and professional fees relating to the procedures carried out.
This arrangement answers a specific need. A single column cost framework, updated by overwriting the initial figures, loses the record of the forecast and makes divergence impossible to measure. A four column framework preserves both readings and turns the document into a control instrument rather than a snapshot.
The two main headings
The cost framework rests on two fundamental figures, and their distinction is the first thing to settle. Confusing them renders the document unusable.
The works amount covers the work subject to discount and the oneri della sicurezza, the safety costs, which are not subject to discount and are paid to the contractor in full. This is the figure deriving directly from the bill.
The sums at the contracting authority's disposal cover the elements not entrusted to the works contractor. They are treated in detail in the dedicated page, and typically comprise professional fees, taxes, utility connections, any land acquisition, contingencies and provisions.
A full worked example
| Item | Pre tender | Post tender |
|---|---|---|
| A.1 Work subject to discount | 870,000 | 783,000 |
| A.2 Safety costs not subject to discount | 30,000 | 30,000 |
| A Total works amount | 900,000 | 813,000 |
| B.1 Professional fees | 108,000 | 108,000 |
| B.2 Utility connections | 18,000 | 16,400 |
| B.3 Contingencies | 45,000 | 45,000 |
| B.4 Tender and advertising costs | 6,000 | 4,800 |
| B.5 Taxes | 198,000 | 179,000 |
| B Total sums at disposal | 375,000 | 353,200 |
| Project total | 1,275,000 | 1,166,200 |
Two readings of this example warrant attention. The first is the relationship between the bill total and the project total: the works amount represents a little over seventy per cent of the overall cost, and this proportion is typical of an ordinary building project. The second is the behaviour of the safety costs line, which stays unchanged between the two columns because it is not subject to discount, while the work items fall in proportion to the discount offered. The values are illustrative.
A document that accompanies the project
The cost framework does not end with design approval. It follows the works through to closure, recording the tender discount, any variations, savings and reinstatements, and how well it holds up over time depends on the discipline with which it is updated.
One statutory point links the cost framework directly to the construction stage. To meet the additional costs arising from price revision, contracting authorities draw, up to a limit of fifty per cent, on the resources specifically set aside for contingencies in the project cost framework, save for sums already committed contractually, together with any further sums at their disposal allocated to the same project.
The consequence for whoever prepares the cost framework is that the contingency provision is not a general reserve but a resource with a partially prescribed destination. It is a resource whose destination is partly fixed by law.
How to read a divergence
The four column structure exists to produce information, and that information needs reading. Three comparisons yield almost everything that matters.
The first is between the pre tender and post tender columns on the work items line. It measures the effect of the discount and, indirectly, the calibration of the estimate: a very high discount more probably signals a generous estimate than an exceptionally competitive tender, and it is worth checking against the unsuccessful bids.
The second is between forecast and actual on the lines of the sums at disposal. This comparison yields the most useful information for subsequent projects, because the items in this section are estimated with the least analysis and are therefore the most exposed to systematic error.
The third is between the initial contingency provision and its actual use at closure. A provision systematically left unused points to an over cautious estimate tying up resources, one systematically exhausted points to inadequate sizing or to improper use covering gaps in the bill.
None of these comparisons requires particular tools. All of them require the cost framework to have been updated by addition rather than by overwriting, which brings us back to why the four column structure became established practice.
The most frequent errors
A cost framework built by applying percentages to the bill total is the first. It produces a document that is formally complete and without foundation: professional fees depend on the services commissioned, taxes on the applicable regime, connections on the networks actually present.
Confusing safety costs with work items is the second, and has the effect of exposing to discount a component the law protects. A component the law protects ends up exposed to the discount.
Updating by overwriting is the third. It erases the original forecast and makes divergence unreadable, which is the document's principal usefulness.
Omitting the contingency provision is the fourth, and deprives the project of the first resource to draw on both for technical eventualities and for price revision. The project is left without the first resource to draw on.
In private construction
Private work has no statutory cost framework, but the structure transfers and its absence produces a recurring problem. A client shown only the bill total reads it as the final cost of the operation, disregarding professional fees, charges, connections and taxes, and correcting that reading once works are under way is always harder than preventing it.
A budget set out under two headings, the cost of the works and the other elements of the operation, with an explicit line for contingencies, is probably the document with the best ratio between drafting time and disputes avoided. It is probably the minimum worth having outside public works too.
Note: the values used in the example are illustrative and do not constitute price references. Legislative references relate to Italy and are current as at the date of publication: the version in force should be checked before any operational use.