[Direct answer]In the Beijing area, whether the supplementary agreement signed separately after winning the bid is "valid" depends on whether its content deviates from the substantive terms of the bid-winning contract. According to Article 46 of the Bidding and Tendering Law of the People's Republic of China, the tenderer and the bid-winner shall, within 30 days from the date of issuance of the bid-winning notice, conclude a written contract in accordance with the tender documents and the bidder's bid documents, and shall not enter into any other agreements that deviate from the substantive content of the contract. If the supplementary agreement only supplements the non-substantive content of the bid-winning contract and is a true agreement between the parties, it is generally valid; if there are substantive changes (such as price, quality, and construction period), it may be deemed invalid, and the bid-winning contract shall still be used as the basis for settlement. It is recommended to first compare the core clauses of the supplementary agreement with those of the bid-winning contract to determine the nature of the changes before making a decision. For more details, please refer to the following link:Legal services for real estate construction projects.

1. Problem background and typical scenarios

Disputes over "black and white contracts" in the construction industry are very common. Typical scenarios include: after bidding, the employer lowers the bid price, changes the construction period, or adjusts the quality standards through supplementary agreements, meeting minutes, or memorandums; the bid-winning contract is a formality for filing or registration, while the parties actually perform another supplementary agreement; and due to price increases for materials or changes in the project scope, the parties agree to adjust the price but worry about the validity of the agreement. Many contractors are confronted with the defense of "invalid supplementary agreement" when settling accounts, or find it difficult to assert their rights based on supplementary agreements they have signed that deviate from the bidding requirements. Such disputes involve the conflict between mandatory bidding regulations and contractual freedom, and the pace of handling and the organization of evidence directly affect the settlement results. The issues of contract validity can be addressed in conjunction with related provisions.Business and contract dispute resolution services for enterprisesCoordinated assessment.

II. Key points of contention

There are three key points of dispute regarding the effectiveness of the supplementary agreement. Firstly, whether the amendment constitutes a "substantive content": the scope of the project, the construction period, the project quality, and the project price are usually regarded as substantive terms, and amendments are easily deemed to deviate from the bid-winning contract. Secondly, the hierarchy of effectiveness: when the filed contract, the bid-winning contract, and the supplementary agreement conflict with each other, which one should be used as the basis for settlement? This needs to be determined in accordance with the mandatory provisions of the bidding and tendering process. Thirdly, evidence of actual performance: which contract is used by both parties for settlement, payment, and signing of certificates will affect the court's determination of the true intention of the parties. For matters involving project payment settlement, reference can be made to the relevant provisions of the "Regulations on the Management of Construction Contracts" issued by the Ministry of Housing and Urban-Rural Development in 2003.Creditor-debtor relations and enforcement case servicesPromote the collection of payments.

III. Professional analysis by Hengluo Lawyers

Based on practical experience in handling construction contract disputes, the most common issues in disputes over supplementary agreements concern the determination and evidence of "substantive changes". According to the Bidding and Tendering Law and its implementing regulations, the tenderer and the successful bidder are not allowed to enter into other agreements that deviate from the substantive content of the contract. This provision aims to maintain the order of bidding and tendering and fair competition. In practice, Hengluo Lawyers usually recommend the following: Before signing a supplementary agreement, first review whether it involves core clauses such as price, construction period, quality, and scope; for changes that are truly necessary, try to complete them through legal procedures (such as re-tendering or filing changes), and fix the true intention of both parties with visas, meeting minutes, etc. When a dispute arises, focus on collecting the tender notice, tender documents, successful bid contracts, and actual performance certificates to prove which contract is the basis for the parties' actual performance. For the protection of the contractor's rights and interests, it can be followed up with legal actions.Real estate sales and construction project servicesDevelop a litigation strategy.

IV. Practical suggestions and legal basis

The core basis is Article 46 (prohibiting the conclusion of other agreements that deviate from the substantive content) and Article 59 (liability for violations) of the "Bidding and Tendering Law of the People's Republic of China" (implemented on January 1, 2000 and amended on December 27, 2017); as well as Article 57 of the "Implementation Regulations of the Bidding and Tendering Law of the People's Republic of China" regarding the prohibition of amendments to the substantive content of the contract, such as the subject matter, price, quality, and performance period. Practical suggestions: After the bidding and tendering, strictly sign the contract according to the bid-winning contract to avoid signing conflicting agreements separately; if it is necessary to supplement, it shall be limited to non-substantive matters and go through legal procedures; keep the bid-winning documents, contracts, and actual performance evidence; and when settling disputes, prioritize claiming based on the bid-winning contract. For the overall review of the construction contract, it can be combined withSpecial servicesEvaluate the risks.

5. Hengluo Law Firm's Advice

The supplementary agreement is not necessarily invalid. The key issue is whether it deviates from the substantive content of the bid-winning contract. Before signing a supplementary agreement with the employer, the contractor should check whether the core terms such as price, construction period, quality, and scope conflict with the bid-winning contract. For changes that have already been implemented, fix the evidence with visas and meeting minutes to avoid verbal agreements. When handling similar cases in Beijing, the court applies stricter rules to mandatory bidding and tendering requirements. It is recommended to organize bidding and tendering materials and contract performance materials as soon as possible. If there are doubts about the validity of the supplementary agreement, it can be verified through legal means.Real estate construction project servicesMake an appointment for an assessment and, if necessary, initiate litigation or arbitration to protect your rights.

VI. Frequently Asked Questions

Q1: I think the supplementary agreement deviates from the bid-winning contract. Is there a high chance of winning the lawsuit if I claim that it's invalid?

The supportability of the claim depends on whether the changes involve substantive clauses. According to Article 46 of the Bidding and Tendering Law and its implementing regulations, the tenderer and the successful bidder shall not enter into any other agreement that deviates from the substantive content of the contract; if the supplementary agreement makes substantive changes to the core clauses such as the project price, construction period, quality, and scope, your claim that this part is invalid and that the settlement shall be based on the successful bid contract is usually more likely to be supported. However, if it is merely a non-substantive supplement and reflects the true intention of both parties, it is difficult to be deemed invalid. The key to success or failure lies in whether the evidence can prove the nature of the changes and the facts of the bidding and tendering. It is recommended to first compare the core clauses of the two documents and then decide on the claim path. Do not easily believe in unrealistic promises of victory.

Q2: What evidence is needed to claim that the supplementary agreement is invalid or that the settlement should be based on the bid-winning contract?

The core evidence includes: the bid-winning notice and tender documents, the bidder's bid documents (proving the substantive content of the bid-winning contract), the filed contract or the text of the bid-winning contract, the supplementary agreements signed separately (proving the content of the amendment), the actual performance certificates of both parties (payment records, project visas, meeting minutes, settlement notes, proving the basis of actual performance), as well as correspondence and communication records. The organization of evidence should focus on three points: "substantive terms of the bid-winning contract - the nature of the amendment in the supplementary agreement - the actual performance situation". If any materials are missing, the court may be requested to retrieve the bidding and tendering filing materials. Never give up the right to settlement just because the evidence is weak.

Q3: How much will it cost in attorney's fees and litigation fees to sue for the validity of a supplementary agreement for a construction project?

The litigation fees are calculated based on the amount of the litigation request (usually the disputed project price) in accordance with the "Measures for the Payment of Litigation Fees", and are borne by the losing party in stages. Since the subject matter of construction projects is usually large, the litigation fees are correspondingly higher. Lawyer's fees are related to the complexity of the case, the subject matter, and the lawyer's qualifications. They can be charged on a fixed-fee, hourly, or percentage-of-the-subject-matter basis, with the specific terms subject to the contract of entrustment. There is no unified government pricing for these fees. In cases involving property rights, contingency fees are subject to a maximum percentage limit. It is recommended to calculate the project payment that can be claimed and the cost-benefit ratio before suing, make rational trade-offs for parts that are obviously unfounded, and focus on the core disputes to control costs.

Q4: How long does it usually take to resolve disputes over supplementary agreements for construction projects?

Such disputes usually require first applying for arbitration or initiating litigation in accordance with contractual agreements or legal provisions. Civil litigation is generally concluded within six months in the first instance and three months in the summary procedure; construction projects often require extended time due to appraisals (cost and quality), which may take more than a year. If an appeal is filed, the second instance generally takes three months. For disputes involving project cost appraisals, the appraisal period will significantly prolong the overall timeframe. Overall, it often takes more than a year from case filing to debt collection. It is recommended to fix the visa and settlement materials during the construction process and initiate legal action as soon as possible after a dispute arises, to avoid the loss of evidence affecting the timeframe and outcome of the case.

Q5: If I find that the supplementary agreement might be invalid, what should I do specifically?

It is recommended to proceed in four steps: First, sort out the bid-winning notice, tender documents, and bid-winning contracts, and clarify the substantive clauses; Second, compare the supplementary agreement item by item, and mark the conflicting contents such as price, construction period, quality, and scope with the bid-winning contract; Third, collect evidence of actual performance (payments, visas, meeting minutes) to prove the true settlement basis; Fourth, if no agreement is reached, apply for arbitration or litigation according to the contract dispute clauses, and claim to use the bid-winning contract as the settlement basis. Throughout the process, keep all written materials and, if necessary, entrust a lawyer to review and negotiate to prevent the other party from using the invalid agreement as a defense to reduce the project payment.

The above Q&A is mainly based on the judicial practice in Beijing. There may be differences in the adjudicative approach in different regions. It is recommended to consult a professional lawyer based on the specific circumstances of the case.

If you are facing similar problems, it is recommended that you consult a professional lawyer as soon as possible with the relevant evidence materials to avoid missing the statutory time limit.Legal services for real estate transactions·Beijing Henglu Law Firm

Disclaimer: This article is compiled based on the current effective laws and regulations and public adjudication rules, and is for general reference only. It does not constitute a formal legal opinion on specific cases. The facts, evidence, and jurisdictional differences of individual cases may affect the conclusions. In case of disputes, please consult a practicing lawyer in time.