Invalidation of the contract is carried out in accordance with Art. 168 Civil Code. The criterion in this case is the non-compliance of the transaction with the standards. Let us consider in more detail how the contract is declared invalid. 
General information
Prescriptions may have the force of law or regulation. When a transaction is recognized as null and void, the industry affiliation of norms with which it contradicts does not matter. However, the law may recognize some disputable transactions, not insignificant, and provide for certain consequences. An example is Art. 162 on the consequences of non-compliance with the usual written form and paragraph 3 of Art. 572, which describes the circumstances that entail the recognition of a gift contract as invalid.
The law identifies a group of insignificant transactions that contradict the foundations of morality and the rule of law. The norms establish not only the procedure in accordance with which the recognition of the contract is invalid, but also provides for consequences of confiscatory nature.
The foundations of the rule of law are the norms established by the state on social, social and economic structure. They are aimed at respecting and observing the prescribed regime, ensuring prescriptions and protecting the freedoms and rights of citizens.
Classification
Invalid contracts with defects may be recognized:
- Subject composition. This flaw entails, for example, invalidation of contracts concluded with legally incompetent citizens, in violation of the authority of a legal entity that goes beyond its legal capacity.
- Will and expression of will. In this case, we are talking about transactions completed without an internal message, as well as if it is formed incorrectly.
- Content. Transactions made for purposes that are obviously contrary to the foundations of morality and the rule of law, feigned and imaginary agreements are considered void.
- Forms. This flaw entails, for example, the invalidation of a loan agreement drawn up not in accordance with the rules provided for in the legislation, as well as the nullity of transactions that have not passed state registration and are not certified by a notary public.
The disadvantage of any or several components of the transaction - non-compliance with applicable standards - leads to nullity. The recognition of the invalidity of contracts relates to the elimination of property consequences arising as a result of execution.
Intent
At least one of the parties may have it invalidated. Judicial practice proceeds from the generally accepted definition of intent, since there is no interpretation of this concept in the Civil Code. In modern law, they consider understanding the unlawfulness of the consequences of the transaction and the desire for their occurrence or assuming them. Invalidation of the contract is allowed with proof of intent, and not with suspicion of it.
Effects
In the event that both parties have intent in fulfilling the terms of the contract, all that they receive is deducted to the income of the Russian Federation. If the obligations are fulfilled by only one participant, then everything acquired and due to the first is withdrawn from the other. This also goes to the income of the Russian Federation. If the intention is on one side, everything that it received (if the terms of the contract were fulfilled) should be given to the other side. In this case, the last received or due is withdrawn to the income of the Russian Federation. 
Fake and imaginary deals
They are also invalidated.An alleged transaction is one that is not aimed at creating the corresponding legal consequences. It is recognized as such regardless of the method of conclusion and the actual fulfillment of obligations under the contract. A deal is considered sham, which is also not aimed at creating the consequences arising from it. But at the same time, she covers up another will of the participants. As a result, the contract concluded between the parties in the specified case is recognized as invalid. In such situations, the rules on transactions that the parties actually provided are applicable. For example, instead of buying and selling, there was a free transfer of property. At the same time, it is framed as a paid transaction. This situation involves the recognition of the contract of sale invalid. If feigned and imaginary transactions cover agreements concluded with a purpose that contradicts the foundations of morality and the rule of law, then the consequences shall be confiscated. They are provided for in Art. 169 Civil Code.
Citizen disability
If a person is recognized as such, the contract is considered invalid. Disability is established in the manner prescribed by law. Recognition of a citizen as such is carried out in court if, due to a mental disorder, he is not able to understand the meaning of his behavior and direct it.
The invalidity of a contract signed by a legally incompetent person shall entail non-occurrence of the legal consequences that are provided for by it. In case of fulfillment of obligations, bilateral restitution (reimbursement) of property in kind is carried out. If it is impossible to return, a monetary compensation is assigned. If the legally capable participant was or should have become aware of the incapacity of the other, he is obliged to compensate for the real damage. The contract may be recognized and valid. This is the case if the benefit for the legally incapable is established. Similar consequences entail the conclusion of an agreement with a person with limited legal capacity. The only difference is that these persons are entitled to commit household small deals. 
A special case
An agreement that has been concluded by a legally competent person may be declared invalid. This is the case if at the time of signing he could not direct his actions and did not understand their significance. A claim for invalidating a contract may be filed by a capable citizen himself, or a person whose rights have been infringed, or other interested parties. The reasons that caused a person's inability to recognize his behavior do not have legal significance. In some cases, they may be due to extraneous circumstances that are not related to the transaction. For example, it can be the death of loved ones, illness, natural disaster, trauma and so on. In some cases, they depend on the citizen himself. For example, he may be intoxicated.
Important point
The fact of concluding a contract at a time when a citizen was not able to direct his behavior and understand the meaning of his own actions must be proved in an appropriate manner. As a rule, in this case there is not enough evidence. In addition to them, it is necessary to provide an opinion of the relevant medical institution. For this, an examination is carried out. 
Transactions completed by persons from 6 to 14 years old
Contracts concluded by citizens at this age may be invalidated. The exception is transactions made at the household level and in other cases specified in paragraphs 2, 3 of Article 28 of the Civil Code. The decision to invalidate the contract is made in accordance with the requirements of the parents or guardians. However, the transaction can also be completed to the benefit of the minor. In this case, also at the request of the guardian or parent, it can be recognized as valid. For void transactions of citizens under the age of 14, the consequences provided for in art. 171 CC.These include compensation for actual damage suffered by a minor, and bilateral restitution.
Transactions involving citizens 14-18 years old
If the contract is concluded with a person at that age without the consent of the parent or guardian in the case when it is necessary, then it may be invalidated. This rule does not apply to transactions made by citizens of 14-18 years of age who are considered fully capable. For example, they include persons who have married. Contracts concluded by persons aged 14-18 are considered disputable and may be recognized by the court as partially or fully valid if they entail benefits for minors. The nullity of transactions involves the compensation by the legally capable participant of the actual harm suffered by the legally incompetent, as well as bilateral restitution. 
Misconduct
Contracts in such cases may also be declared null and void. The deal, which was made under the influence of error, ceases to meet the established criteria, because in it the will of the participants is expressed distorted, incorrectly. As a result of this, such an agreement entails a different result than that which was supposed. In order to protect interests and rights, the law provides for the recognition of a transaction as null and void at the request of the erring party. It can be both a citizen and a legal entity. Misconception must exist at the time of the conclusion of the contract and make a difference.
Of importance is the opinion regarding the nature of the transaction or the identity or such properties of its subject matter that can significantly reduce the possibility of its intended use. The misconception regarding the motives for concluding a contract does not matter much. When identifying a distortion of will, the rules specified in paragraph 2 of Art. 167, - mutual restitution. The party, upon the declaration of which the contract is declared invalid, has the right to demand compensation for the real damage caused to it if it is proved that another participant is guilty of the occurrence of an error.
Limitation period
A claim for the application of the consequences of the nullity of the contract can be submitted within 3 years from the moment when its execution began. The established period applies to applications whose statute of limitations has not expired by the Civil Code until July 16, 2005 (before the entry into force of Federal Law No. 109). A claim for declaring the contract disputable and applying the consequences of its invalidity may be filed within a year from the moment of termination of the circumstances under the influence of which it was concluded, or from the day on which the plaintiff became or should have become aware of the facts that serve as the basis for establishing nullity . 
Finally
To avoid negative consequences, it is necessary to follow the established procedure. A sample contract must contain all the necessary details, indicate exactly the circumstances, obligations, rights of the parties. The agreement also provides for the liability of the parties. The sample contract, among other things, provides for a section on resolving disputes regarding the fulfillment of obligations.
