1, one party benefits;

2. The other party suffers losses;

3. There is a causal relationship between one party's benefit and the other party's loss.

Provisions on unjust enrichment:

1. If the beneficiary doesn't know and shouldn't know that the obtained benefits have no legal basis, and the obtained benefits no longer exist, he will not assume the obligation to return the benefits;

2. If the beneficiary knows or should know that the benefits obtained have no legal basis, the person who has suffered losses may request the beneficiary to return the benefits obtained and compensate the losses according to law;

3. If the beneficiary transfers the obtained benefits to a third person free of charge, the victim may request the third person to undertake the obligation of return within the corresponding scope.

Specific procedures for filing a case:

1. When the plaintiff brings a lawsuit to the court, it shall submit the complaint and relevant evidential materials, and submit a copy of the complaint and evidence according to the number of defendants; At the same time, fill in the list of complaints in duplicate, one for the court and one for the plaintiff;

2. After accepting the complaint submitted by the parties, the court shall sign the complaint. Upon examination, those who meet the conditions for filing a case shall immediately file a case, and at the same time, the parties shall be served with the Notice of Acceptance of the Case, the Confirmation of Delivery of Legal Documents by the Parties, the Notice of Litigation, the Notice of Mediation and the Notice of Paying Litigation Fees;

3. The court decided to file a case and arrange it immediately. The schedule includes determining the date, time, court and presiding judge of the court session, and serving court summons on the parties;

4. The parties can pay the fees at the charging points of each court within seven days after receiving the notice of paying the litigation fees issued by the court;

5. Payment method can be selected by yourself;

6. Both parties shall immediately exchange the special voucher (receipt) for litigation expenses with the special voucher for litigation expenses issued by Agricultural Bank of China.

To sum up, the case of unjust enrichment must meet three conditions, one party benefits; There is a causal relationship between one party's benefit and the other party's loss.

Legal basis:

Article 985 of the Civil Code of People's Republic of China (PRC)

If the beneficiary has no legal basis to obtain improper benefits, the person who has suffered losses may request the beneficiary to return the benefits obtained, except in any of the following circumstances:

(1) Remuneration for performing moral obligations;

(2) Liquidation before the maturity of debts;

(three) knowing that there is no obligation to pay.