Amendments with Claude: trace what changes in the contract

Prepare a contract amendment with Claude →

A renovation site has been running for two months when the client asks, during a routine visit, to add an extra bathroom upstairs. The architect agrees verbally, takes notes, and the contractor starts partition work the following week. Three weeks later, the client is surprised by the amount added to the progress invoice: they thought that service was "included in the original budget." Nothing had been written between the verbal agreement and the start of the work.

An amendment (avenant) is not an administrative formality to be tidied up afterwards: it is the only legal route for modifying a contract that, once signed, already has the force of law between the parties. A change accepted verbally and carried out before any written record puts both the architect and the client in a position where the scope actually agreed becomes hard to establish if a later disagreement arises over the amount or extent of the change.

This article details why a contract can only be modified by the mutual consent of the parties, why the order between signature and execution matters as much as the content of the amendment, and the method for preparing an amendment that precisely traces what changes without rewriting what stays the same.

Summary

1. An amendment modifies a contract that already has the force of law between the parties
2. Sign before executing: why the order of operations matters
3. What an amendment must trace, item by item
4. Preparing an amendment step by step
5. When an amendment is not enough
6. What we observe among independent architects
7. Training to make amendments more reliable
8. Frequently asked questions

An amendment modifies a contract that already has the force of law between the parties

A signed maîtrise d'œuvre contract "has the force of law" for the architect and their client within the meaning of Article 1103 of the Civil Code: neither party can unilaterally change its content, even for an adjustment that looks minor against the overall project.

Mutual consent, the only route to modification

Article 1193 of the Civil Code provides that "contracts may only be modified or revoked by the mutual consent of the parties, or for causes the law authorizes." An amendment is precisely the instrument that formalizes that mutual consent on a specific point of the contract — the scope of the commission, fees, the schedule — without which the modification remains, legally, a mere unrecorded discussion.

What does not change stays governed by the original contract

An amendment does not rewrite the contract: it completes it on the points identified, leaving every clause unaffected by the change untouched. An amendment that rewords entire articles of the original contract with no connection to the requested change introduces a risk of contradiction with the signed version — precisely what a targeted document should avoid.

Sign before executing: why the order of operations matters

A change accepted verbally and carried out before any signature puts both parties in a fragile position: the architect has performed or had performed a service whose price has not yet been formally settled, and the client may, in good faith or not, later dispute the amount they believe they agreed to.

The risk of executing first and negotiating afterwards

Executing first and negotiating afterwards reverses the logic of Article 1193: at the moment the additional service is carried out, no written mutual consent yet covers it, and its payment becomes an after-the-fact adjustment rather than a prior contractual agreement. That is a weaker position for the architect in the event of a disagreement, since the price of the service was never formally fixed before it was delivered.

What to do in an emergency, while the formal amendment is prepared

When the site schedule forces a fast decision — a contractor mobilized on site who cannot wait two weeks over a point of detail — good practice is to get the principle and the intended amount confirmed in writing, even through a short exchange, before letting execution start, then to formalize the complete amendment as soon as possible afterwards. That prior written exchange does not replace the amendment, but it documents a consent that, without it, would have left no trace at all.

What an amendment must trace, item by item

A reliable amendment identifies, for each change, the prior state, the proposed modification and the effective date — never merging several changes into a vague wording.

This before/after structure, repeated for each affected item, prevents an amendment from being reduced to a single lump sum that cannot be traced back to what it actually covers months later.

Preparing an amendment step by step

Step 1: Collect the signed contract and any amendments already accepted. An amendment is always read in light of the contract it modifies and of changes already recorded; ignoring an earlier amendment risks counting the same fee supplement twice.

Step 2: Precisely identify the affected article or articles. Scope, fees and schedule are not necessarily all affected by the same change; an amendment that only touches the commission must not reword financial clauses that remain unchanged.

Step 3: Describe the prior state before wording the new proposal. This description makes it possible to check that the announced financial impact is not already covered by an earlier amendment or by an existing clause of the original contract.

Step 4: Set an explicit effective date. An amendment with no effective date leaves ambiguity about when the new scope or new rate applies, particularly for services already underway.

Step 5: Have the amendment signed before the services it covers are performed. It is this order — signature, then execution — that gives the amendment its full value as mutual consent within the meaning of Article 1193 of the Civil Code, rather than a late adjustment of a verbal agreement.

When an amendment is not enough

A properly drafted amendment does not cover every situation that arises during a commission. A change that calls the overall economics of the contract into question — a project whose brief changes to the point where the original commission bears little resemblance to what is now requested — is not handled through a one-off amendment: it calls for a full renegotiation, or even a new contract, to avoid stacking amendments that, taken together, become inconsistent. A persistent disagreement between the parties over the very principle of a change — the client believing a service was included in the original budget, the architect believing the opposite — is not resolved by drafting an amendment that one party would refuse to sign: it calls for a contractual discussion before any further step, with the help of a legal professional if the disagreement persists. An amendment prepared with AI assistance remains, in every case, a draft: it must be reviewed and its content confirmed by both parties before signature, since generating the document alone proves no acceptance.

What we observe among independent architects

In our exchanges with independent architects about their amendments, the difficulty is almost never understanding that a change must be written down: that reflex is widely shared. What costs time is finding the exact version of the contract currently in force among several email exchanges, checking that an earlier amendment did not already partially cover the new change, or wording a before/after table that stays readable without rewording the whole contract. That is a traceability task, not a doubt about the principle — and it is exactly what a well-structured amendment template makes easier, without ever excusing the parties from signing before the additional service is carried out.

Training to make amendments more reliable

An amendment template is not enough if its before/after table is filled in without checking earlier amendments or consistency with the original contract. For an architect practising as a self-employed professional (NAF code 7111Z in France), the FIFPL fund covers part of the cost of Qualiopi-certified training under 2026 criteria set at €300 per day and €900 per year, with e-learning capped at 50% of the daily rate. This funding must be arranged before training starts, not after.

Frequently asked questions

Is a verbal agreement on a change to the commission enough?

No: a verbal agreement can amount to consent under general contract law, but it leaves no enforceable proof if the parties later remember the agreed amount or scope differently. A written, signed amendment remains the only way to fix, in a verifiable manner, what both parties actually accepted. In the event of a later dispute, it is this document, not the memory of the exchanges, that will govern.

Can an additional service be carried out before signing the amendment that covers it?

This is common practice but risky: at the moment the service is carried out without a signed amendment, its price has not yet been formally settled through written mutual consent, which weakens the architect's position in the event of a dispute. When the schedule forces things to move quickly, a short written exchange confirming the principle and the amount, before execution, limits this risk while the full amendment is being formalized. That preliminary exchange should then be carried over into the formal amendment as soon as possible, so this interim confirmation does not end up standing in indefinitely for the final contractual document.

Must an amendment reword the entire original contract?

No: an amendment should stay focused on the articles actually affected by the change, leaving unaffected clauses untouched. Rewording entire passages of the contract unrelated to the requested modification increases the risk of contradiction between the two documents rather than clarifying what changed. The before/after table remains the safest format for this: it visually isolates what changes without forcing a rewrite of the clauses that stay identical.

What should be done if a client disputes an amendment after signing it?

Having signed a document does not legally prevent a later dispute, but a clear amendment, dated and referenced to the original contract, provides solid proof of what was accepted. In the event of a persistent disagreement over how to interpret a clause, the discussion should involve a legal professional, rather than a new version of the document drafted unilaterally by one of the parties. Keeping every exchange that predates signature — proposals, emails, meeting notes — also helps reconstruct the context in which the amendment was negotiated, should its interpretation ever be disputed.

Do fees added by an amendment follow a standard percentage?

No: as with the original contract, additional fees set by an amendment are freely negotiated between the parties, with no statutory scale or imposed reference percentage. The amount used must match the real agreement on the added service, not a default value copied from a generic template without verification. As with the original contract, that amount must be traceable back to the commercial exchange that set it, not reconstructed after the fact from a rough estimate.

A reliable amendment rests on three elements that do not change from one site to the next: a before/after table that precisely identifies what changes, a signature obtained before the relevant service is performed, and unaffected clauses left intact. Once that foundation is in place, it is exactly what the amendment generator applies automatically, leaving both parties the decision to accept the change that belongs to them alone.

Before the amendment, our method for preparing a maîtrise d'œuvre contract details the structure of the document it comes to modify, and once the change is validated, our method for the final invoice revisits how to reflect accepted amounts in final billing.

Training 100% fundable via OPCO/FIFPL. Qualiopi-certified programme. To structure your amendments and contractual documents with AI as part of our AI for architectural management training, contact Educasium and specify your status (employee, self-employed, business owner) and your goal.