Three distinct notions
| Notion | What it allows |
|---|---|
| The variant | a solution differing from the base solution |
| The option | additional work, whose take-up is decided later |
| The conditional stage | part of the contract whose execution depends on a later decision |
The variant concerns the how, proposing another way of achieving the same result.
The option concerns the how much, adding work or not.
The conditional stage concerns the whether, subordinating execution of part of the contract to a future decision.
Their effect on the estimate of the contract
A regulatory point often neglected, with direct consequences. It concerns calculation of the estimated value of the contract.
Calculation of the estimated value of a contract is based on the total amount payable excluding tax, and includes notably all options required or authorised, all lots, all repetitions, and all firm and conditional stages. Options and renewals therefore count towards the threshold.
The practical consequence is significant: a contract whose firm part stays below a threshold but whose conditional stages exceed it must be estimated on the total. Division does not allow escape from the rules applying to the amount.
The three regimes of variants
They differ in what they impose on the tenderer. Some are mandatory, others left to the tenderer's initiative.
The mandatory variant must be submitted. A tender not containing it is incomplete.
The authorised variant may be submitted. The tenderer chooses, and the tender remains valid if it is not proposed.
The free variant is proposed at the tenderer's initiative, under the conditions the contract documents provide.
The contract documents must state what is admitted, and absent any indication, free variants are in principle inadmissible.
How to structure them in the bill
Four structuring rules, determining the readability of the document. They concern the placement, the identification and the total of each mechanism.
Separate the parts physically. Base solution, variants, options and conditional stages must form distinct sets, with their own totals.
Never mix an option item into the base total. That is the commonest error and it makes comparison impossible.
Make each set self-contained. A variant must contain all the items it modifies, including those it deletes, with negative quantities or explicit statements.
Provide for the fate of shared items. A variant modifying the structure may affect items elsewhere in the bill, and those effects must appear.
Why comparison distorts so easily
Three mechanisms recur regularly.
Scopes diverge between tenders. If the documents do not tightly frame the content of a free variant, each contractor proposes a different one and the prices no longer compare.
Options are priced differently depending on whether they are seen as likely. A contractor anticipating take-up of an option may adjust base prices accordingly.
Cross-effects are not visible. A variant lightening one trade may burden another, and a total per set does not show it if the sets are not complete.
Hence the central rule: comparison holds only between sets of the same scope. Base against base, variant against corresponding variant, never one overall total against another.
What this means for a professional
Four rules.
Define the content of each authorised variant strictly, or comparison will be unworkable.
Estimate the contract on the total, options and conditional stages included, before choosing the procedure.
Check the self-sufficiency of each set in the bill, notably items deleted by a variant.
Compare by set, never by overall total. A total adding different scopes means nothing.
This article reflects the position of the rules at the date of checking and serves professional orientation. It does not constitute legal advice and does not replace assessment of the individual case.