Promise to sell an existing home: unilateral promise or compromise
Verified 10 April 2026 - Public Service / Directorate of Legal and Administrative Information (Prime Minister)
For the purchase and sale of an existing home, it is possible to use 2 main types ofpre-contract : the unilateral promise of sale (often called promise to sell) and the synallagmatic promise of sale (commonly called sales agreement). These two acts are based on different legal rules. We present you the information to know.
Unilateral Promise of Sale
The unilateral promise of sale is a contract by which the seller (called the promising) undertakes to sell its property to a specified person (the beneficiary), leaving it the possibility of deciding, within a period fixed by the 2 parties, whether or not they want to buy.
The potential purchaser benefits, in fact, from right of option. He is thus free to exercise the option (to buy the property) or to renounce it (not to buy) within the prescribed period.
All the essential elements of the sale (goods, prices, etc.) are already determined in the promise.
For the sale to be formed, all that is needed is the subsequent consent of the beneficiary.
FYI
During the entire period of validity of the promise, the seller may not not leave your property on the market or sell it to another person.
The promise to sell is established by a authentic act or by a act under private signature.
Warning
When the seller is a natural person, the unilateral promise of sale must mandatory be ascertained by a authentic act where:
- its validity period exceeds 18 months
- or that an extension of the promise has the effect of extending its total duration beyond 18 months.
Where the unilateral promise of sale is established by an act under private signature, it must be registered within 10 days from its acceptance by the purchaser. In this case, one of the parties (seller or buyer) must file or send the deed in 2 original copies to the land advertising and registration service of the location of the real estate.
Who shall I contact
Registration costs €125.
If the promise does not comply with these formal conditions, it is null and void. This means that it is legally non-existent.
To facilitate the drafting of the unilateral promise, the seller and the buyer must prepare certain documents.
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Seller
The seller must, depending on the situation, present the following documents:
- Identity document, possible marriage contract or Civil partnership agreement for natural persons
- Extract Kbis and a copy of the statutes of the business for legal persons
- Copy of the title deed
- If the property is a detached house: Plans, cadastral references, building permit, work authorization and certificate of conformity issued to it
- Documents mentioning the easements
- If the property is occupied by a third party: copy of the current rental contracts or documents justifying the departure of the former tenants (tenant's leave, landlord leave)
- If the good is one batch in a collective building: documents relating to co-ownership (summary sheet, condominium rules, division descriptive report, minutes of general meetings of the last three years, maintenance log, global technical diagnosis, multi-annual work plan or project, pre-dated statement by the trustee)
- If the property is located in a subdivision: Specifications of the subdivision
- If the property is part of a 'trade union association of owners (ASL): copy of ASL statutes
- Font ofproperty and casualty insurance valid
- Proof of the condition of the immovable with regard to thesanitation (control, maintenance contract, connection bill, ...).
- Technical diagnostics file (lead finding, asbestos condition, condition termitesinformation, medulla, gas and/or electrical installation status, energy performance record etc). Diagnostics must be valid as of the date of promise.
Type of documents | Duration of validity |
|---|---|
Asbestos finding | Permanent validity |
Lead | 1 year |
Termites | 6 months |
Gas (installation over 15 years old) | 3 years |
Electricity (installation over 15 years old) | 3 years |
Energy Performance Record (EPD) | 10 years |
State of risks (natural, technological, mining risks, etc.) for the areas concerned | 6 months |
Energy Audit | 5 years |
Acquirer
- Identity document
- Extract Kbis and copy of the statutes for a legal person
To be valid, the unilateral promise of sale must contain several pieces of information. Indeed, in practice, the promise must contain all the essential elements and clauses intended to form the final agreement, so that the exercise of the option by the beneficiary (purchaser) is sufficient to form the sale.
Its content must be lawful and certain, i.e. the elements necessary for the formation of the sale (in particular the description of the property and the price) must be clearly defined or can be determined objectively, without ambiguity, at the time of the exercise of the option.
Warning
If one of the parties is aware of information that may be decisive for the consent of the other party, it must inform the other party. This decisive information concerns the content of the contract, the status of the parties or the characteristics of the property sold. This could be, for example, a project involving expensive work in the condominium, the existence of significant cracks or a structural problem in the building or a risk of flooding.
Failure to comply with this duty of information may result in the cancelation of the contract.
Information about the seller and the buyer
The promise to sell must mention the identification of the parties (seller / buyer) their capabilities and their respective coordinates.
Information about the property
The promise to sell must include the following information:
- Address of the property
- Cadastral references
- Precise description of the property: nature (house, apartment...), area, number of rooms, equipment, presence of a garden or a balcony etc.
- Origin of the property (date of previous deed of sale, name of previous owner, notarial deed...)
- Existence of a mortgage, of a bondage or a citizenship
- Indication of whether the area where the property is located is reserved for new construction of dwellings for exclusive use as a principal residence
- Information on the condition and situation of the property (technical diagnostics folder prepared by a professional)
- For a condominium, information specific to the condominium
- For housing in subdivision, specifications, subdivision by-law and the statutes of the free trade union association which manages the common spaces and facilities.
Information about the sale
- Sale price and payment terms (paid in cash with or without the help of a mortgage)
- Period of validity of the promise to sell
- Deadline for signature of the definitive deed of sale
- Information on the conditions for the exercise of the option (form, time limit, notification address, proof of the date of receipt)
- Information on the conditions for exercising the right of withdrawal
- Amount of capital cost allowance
- Date of availability of the property
- Amount of fees the professional in charge of the sale (if there is intervention of a professional) and to whom the payment is responsible.
FYI
Some suspensive conditions may be included in the promise to sell. It may be the suspensive condition for obtaining a mortgage, obtaining a contract, work to be carried out by the seller before the sale or the purging of the right of pre-emption.
The way to sign a unilateral promise of sale depends on the form to choose for the act (act under private signature or authentic act).
Signature of a unilateral promise of sale by authentic instrument
The unilateral promise of sale made by a notary (authentic instrument) can be signed on paper or on an electronic medium. In both cases, each party must sign the deed.
Please note
The electronic signature shall have the same value as a handwritten (paper) signature, provided that:
- It makes it possible to clearly identify its author
- And ensure that the content of the document has not been changed.
The original document is kept by the professional (notary). Each party must keep a copy of the document or be able to easily access it in a dematerialized format.
FYI
In the case of an electronic document, a download link for the document is available immediately after signature. It allows you to access and preserve the document without delay.
Signature of a unilateral promise of sale by private deed
The unilateral promise of sale in the form of a private deed must be signed on paper. Each party signs the deed.
The promise is made in 2 original copies (1 for the seller, 1 for the buyer), except when a unique original is kept by a professional (real estate agent).
Warning
The electronic signature of a unilateral promise of sale does not allow its registration with the land advertising services. However, registration is an essential formality for the act to be valid. A unilateral promise of sale made in electronic format will therefore be null and void since it cannot be regularly registered.
In principle, the buyer does not have to pay the seller any money when signing the unilateral promise of sale. This is not a condition of validity of the act.
However, the promise often provides for the payment of a called amount of money capital cost allowance. It pays the price of the exclusivity of the property granted to the beneficiary (potential buyer) by the seller.
Warning
When the duration of the unilateral promise to sell exceeds 18 months, the payment of a capital cost allowance for a minimum amount of 5% of the selling price is mandatory. It is paid into the hands of the notary who will serve as sequestration.
In practice, the amount of the capital cost allowance is between 5% and 10% of the selling price. It is customary for this amount to be paid to a third party sequestration and not directly to the seller. This fixed asset compensation is thus collected and blocked until the conclusion of the contract of sale on the escrow account from the notary.
The nature of the capital cost allowance depends on the outcome of the promise:
- If the sale is made, the amount paid is deducted from the sale price of the property. It is considered as a down payment.
- If the suspensive conditions provided for in the compromise do not materialize (e.g. loans not obtained), the promise lapses so that the sum paid is returned in full to the purchaser.
- If the purchaser simply renounces the purchase without legitimate cause (for example, the seller's failure to provide essential documents, conceal decisive information or sell a property that did not comply with what was intended) or failure to fulfill a suspensive condition, the sum is retained by the seller.
The unilateral promise of sale contains several deadlines, namely:
- Time to lift option (period during which the beneficiary may decide to purchase), freely determined by the parties. It can be set by a specific deadline, by a time limit with a determined starting point (for example, 6 months from the signing of the promise or 15 days after the fulfillment of the last suspensive condition) or by reference to an event.
- Deadline for completion of suspensive conditions. It can be the same as the option's withdrawal period, longer or shorter. The parties shall freely set that time limit. The only exception concerns the condition for obtaining a loan for which a minimum period of 1 month is imposed from the signature of the agreementauthentic act or the recording of the deed under private seal.
- Time to register for the unilateral promise made under private seal within 10 days of the signature by the parties
- Deadline for retraction 10 days from the notification the unilateral promise of sale relating to a residential immovable, by a non-professional purchaser
- Deadline for signing the deed of sale after the option is exercised. It is freely fixed by the parties.
Seller
In a unilateral promise of sale, the seller is definitively committed to sell as soon as the promise is signed. It cannot therefore, in principle, withdraw. The only exception to this principle concerns the case where the act provides, in a clause, for a right of withdrawal or deprecated from the seller.
Acquirer
THEnon-professional purchaser of a residential property has a right of withdrawal within a period of 10 calendar days. The deadline starts the day after the 1stera presentation of the registered letter notifier the act (unilateral promise) to the purchaser. The cancelation of the sale must be notified to the seller by registered letter with acknowledgement of receipt.
Sales Compromise
The sales agreement, also called synallagmatic promise of sale, is a contract signed between a seller and a buyer.
By this contract:
- The seller undertakes to sell his property (apartment, house etc)
- The purchaser undertakes to purchase this property.
The price and the conditions of the sale are fixed as soon as the compromise is signed.
The act shall note the reciprocal commitmentss of the two parts.
The sales agreement must be in writing. It can take different forms, namely:
- one act under private signature written by the two parties or by a real estate agency
- or an act countersigned by lawyer
- Or a authentic act.
FYI
When the seller is a natural person, the sales agreement must mandatory be ascertained by a authentic act where:
- its validity period exceeds 18 months
- an extension of the promise extends its total duration beyond 18 months.
To facilitate the drafting of the sales agreement, the seller and the buyer must prepare certain documents.
Seller
The seller must, depending on the situation, present the following documents:
- Identity document, possible marriage contract or Civil partnership agreement for natural persons
- Extract Kbis and a copy of the statutes of the business for legal persons
- Copy of the title deed
- If the property is a detached house: Plans, cadastral references, building permit, work authorization and certificate of conformity issued to it
- Documents mentioning the easements
- If the property is occupied by a third party: copy of the current rental contracts or documents justifying the departure of the former tenants (tenant's leave, landlord leave)
- If the good is one batch in a collective building: documents relating to co-ownership (summary sheet, condominium rules, division descriptive report, minutes of general meetings of the last three years, maintenance log, global technical diagnosis, multi-annual work plan or project, pre-dated statement by the trustee)
- If the property is located in a subdivision: Specifications of the subdivision
- If the property is part of a 'trade union association of owners (ASL): copy of ASL statutes
- Font ofproperty and casualty insurance valid
- Proof of the condition of the immovable with regard to thesanitation (control, maintenance contract, connection bill, ...).
- Technical diagnostics file (lead finding, asbestos condition, condition termitesinformation, medulla, gas and/or electrical installation status, energy performance record etc). Diagnostics must be valid as of the date of promise.
Type of documents | Duration of validity |
|---|---|
Asbestos finding | Permanent validity |
Lead | 1 year |
Termites | 6 months |
Gas (installation over 15 years old) | 3 years |
Electricity (installation over 15 years old) | 3 years |
Energy Performance Record (EPD) | 10 years |
State of risks (natural, technological, mining risks, etc.) for the areas concerned | 6 months |
Energy Audit | 5 years |
Acquirer
In particular, the purchaser must submit the following documents:
- Identity document for natural persons
- Birth certificate extract less than 3 months old
- Proof of address
- Proof of family situation (marriage contract, copy of the declaration of Civil partnerships at the registry and Civil partnerships: titleContent, judgment finding the body separation, divorce judgment and non-conciliation order or copy of the divorce summons if the proceeding is pending)
- Extract Kbis and a copy of the statutes of the business for a legal person.
Different types of information must be included in the sales agreement.
Warning
If one of the parties is aware of information that may be decisive for the consent of the other party, it must inform the other party. This decisive information concerns the content of the contract, the quality of the parties or the characteristics of the accommodation sold. Failure to comply with this duty of information may result in the cancelation of the contract.
Information about the seller and the buyer
The compromise must mention the respective contact details of the seller and the buyer.
Information about the property
The promise to sell must include the following information:
- Address of the property
- Cadastral references
- Precise description of the property: nature (house, apartment...), area, number of rooms, equipment, presence of a garden or a balcony etc.
- Origin of the property (date of previous deed of sale, name of previous owner, notarial deed...)
- Existence of a mortgage, of a bondage or a citizenship
- Indication of whether the area where the property is located is reserved for new construction of dwellings for exclusive use as a principal residence
- Information on the condition and situation of the property (technical diagnostics folder prepared by a professional)
- For a condominium, information specific to the condominium
- For housing in subdivision, specifications, subdivision by-law and the statutes of the free trade union association which manages the common spaces and facilities.
Information about the sale
The sales agreement must contain the following information:
- Selling price and the distribution between the price of the property and the price of furniture
- Terms of payment (paid in cash with or without the help of a mortgage)
- Possible suspensive conditions (for example, obtaining a home loanobtaining a contract or work to be carried out by the seller before the sale) and the time limit for the fulfillment of these conditions
- Period of validity of the promise to sell
- Deadline for signature of the definitive deed of sale
- Information on the conditions for exercising the right of withdrawal for a non-professional purchaser
- Date of availability of the property
- Amount of fees the professional in charge of the sale (if there is intervention of a professional) and to whom the payment is responsible.
Let it be in the form of a act under private signature or a authentic actHowever, the sales agreement may be signed on paper or on an electronic medium. In both cases, each party must sign the deed.
Warning
A scanned signature is neither a handwritten (paper) nor an electronic signature. It is a copy of a signature and is therefore not valid.
When the sales agreement is drawn up by deed under private signature, it must be drawn up in 2 original copies (1 for the seller, 1 for the buyer).
Where the sales agreement is drawn up by electronic document, the process used must enable each party to have a copy or to have access to it.
In principle, the buyer does not have to pay the seller any money when signing the sales agreement. This is not a condition of validity of the act.
However, it is common for the sales agreement to provide for the payment of a sum of money, generally called security deposit. It constitutes a deposit, corresponding to 10% the selling price.
This security deposit is collected and blocked until the conclusion of the sales contract on the escrow account from the notary.
If the suspensive conditions provided for in the compromise are not being implemented, the amount paid shall be returned in full.
If the purchaser renounces the purchase, the amount shall be retained by the owner.
When the final deed of sale is signed, it is deducted from the sale price.
The deadlines vary according to the geographical location of the property:
General case
The sales agreement contains several deadlines, namely:
- Deadline for completion of suspensive conditions. The parties shall freely set that time limit. The only exception concerns the condition for obtaining a loan for which a minimum period of 1 month is imposed from the signing of the instrument.
- Deadline for retraction 10 days from the notification the sale agreement for a residential immovable, by a non-professional purchaser
- Deadline for signing the deed of sale definitive. The parties shall freely set that time limit.
FYI
The parties may provide for an extension of the initial time limits. One endorsement the contract is then drawn up under the same conditions as the initial contract.
In Alsace-Moselle
In the departments of Haut-Rhin, Bas-Rhin and Moselle, the private signature sales agreement must be followed by a authentic act sale within 6 months. The parties cannot agree on a longer time limit.
The sales agreement contains several deadlines, namely:
- Deadline for signing an authentic instrument when the compromise is concluded under private signature: in the departments of Haut-Rhin, Bas-Rhin and Moselle, this period is set at a maximum of 6 months. The parties cannot agree on a longer time limit.
- Deadline for completion of suspensive conditions. The parties shall freely set that time limit. The only exception concerns the condition for obtaining a loan for which a minimum period of 1 month is imposed from the signing of the instrument.
- Deadline for retraction 10 days from the notification of the agreement for the sale of a residential immovable, by a non-professional purchaser (individual)
- Deadline for signing the deed of sale definitive. The deadline is freely set by the parties.
Seller
The seller is definitively committed to sell as soon as the sales agreement is signed. It cannot therefore, in principle, withdraw. The only exception to this principle concerns the case where the act provides, in a clause, for a right of withdrawal or deprecated from the seller.
Acquirer
THEnon-professional purchaser of a residential property has a right of withdrawal within a period of 10 calendar days. The deadline starts the day after the 1stera presentation of the registered letter notifier the deed (compromise) to the purchaser. The cancelation of the sale must be notified to the seller by registered letter with acknowledgement of receipt.
The purchaser may use a template letter:
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Definition of synallagmatic and unilateral contracts
Definition of the unilateral promise of sale
Suspensive condition
Act under private signature
Form of promise of sale, registration, mention of price and fees
Registration of the unilateral promise of sale within 10 days
Obligation to mention the use of a bank loan (Article L313-40)
Withdrawal period and prohibition of payments during this period
Obligation to attach a technical diagnostic record to the promise
Authentic instrument and capital indemnity
Explicit mention of new buildings for use as principal residence
Time limit ending on a non-working day
Document template
FAQ
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Notaries of France
Directorate-General for Public Finance (DGFiP)