IFRS 15 defines a contract as an agreement between two or more parties that creates enforceable rights and obligations. For an entity to account for a contract with a customer under IFRS 15, the following criteria must be met:

1. Contracts have Commercial Substance: The contract should have commercial substance, meaning that the risk, timing, or amount of the entity's future cash flows is expected to change as a result of the contract.
2. Approval and Commitment: The parties to the contract have approved the contract (in writing, orally, or in accordance with other customary business practices) and are committed to fulfilling their respective obligations.
3. Identifiable Rights: The entity can identify each party's rights regarding the goods or services to be transferred.
4. Payment Terms: The entity can identify the payment terms for the goods or services to be transferred.
5. Probable Collection: It is probable that the entity will collect the consideration to which it will be entitled in exchange for the goods or services that will be transferred to the customer. This criterion requires an entity to assess a customer's ability and intention to pay the promised consideration.

In other words, the contract should be enforceable, clearly outline the rights and payment terms of each party, and it should be probable that the entity will collect the consideration. If these conditions are not met, the entity may need to reassess the contract or possibly even recognize a loss.