Section 50 in The Indian Contract Act, 1872

Title: Performance in manner or at time prescribed or sanctioned by promise.

Description: The performance of any promise may be made in any manner, or at any time which the promisee prescribes or sanctions. Illustrations (a) B owes A 2,000 rupees. A desires B to pay the amount to A's account with C, a banker. B, who also banks with C, orders the amount to be transferred from his account to A's credit, and this is done by C. Afterwards, and before A knows of the transfer, C fails. There has been a good payment by B. (b) A and B are mutually indebted. A and B settle an account by setting off one item against another, and B pays A the balance found to be due from him upon such settlement. This amounts to a payment by A and B, respectively, of the sums which they owed to each other. (c) A owes B 2,000 rupees. B accepts some of A's goods in reduction of the debt. The delivery of goods operates as a part payment. (d) A desires B, who owes him Rs. 100, to send him a note for Rs. 100 by post. The debt is discharged as soon as B puts into the post a letter containing the note duly addressed to A.

Title: Promisor not bound to perform, unless reciprocal promisee ready and willing to perform.

Description: When a contract consists of reciprocal promises to be simultaneously performed, no promisor need perform his promise unless the promisee is ready and willing to perform his reciprocal promise. Illustrations (a) A and B contract that A shall deliver goods to B to be paid for by B on delivery. A need not deliver the goods, unless B is ready and willing to pay for the goods on delivery. B need not pay for the goods, unless A is ready and willing to deliver them on payment. (b) A and B contract that A shall deliver goods to B at a price to be paid by instalments, the first instalment to be paid on delivery. A need not deliver, unless B is ready and willing to pay the first instalment on delivery. B need not pay the first instalment, unless A is ready and willing to deliver the goods on payment of the first instalment.

Title: Order of performance of reciprocal promises

Description: Where the order in which reciprocal promises are to be performed is expressly fixed by the contract, they shall be performed in that order; and where the order is not expressly fixed by the contract, they shall be performed in that order which the nature of the transaction requires. Illustrations (a) A and B contract that A shall build a house for B at a fixed price. As promise to build the house must be performed before B's promise to pay for it. (b) A and B contract that A shall make over his stock-in-trade to B at a fixed price, and B promises to give security for the payment of the money. A's promise need not be performed until the security is given, for the nature of the transaction requires that A should have security before he delivers up his stock.

Title: Liability of party preventing event on which the contract is to take effect.

Description: When a contract contains reciprocal promises, and one party to the contract prevents the other from performing his promise, the contract becomes voidable at the option of the party so prevented; and he is entitled to compensation from the other party for any loss which he may sustain in consequence of the nonperformance of the contract. Illustration A and B contract that B shall execute certain work for A for a thousand rupees. B is ready and willing to execute the work accordingly, but A prevents him from doing so. The contract is voidable at the option of B; and, if he elects to rescind it, he is entitled to recover from A compensation for any loss which he has incurred by its non-performance.

Title: Effect of default as to that promise which should be first performed, in contract consisting of reciprocal promises

Description: When a contract consists of reciprocal promises, such that one of them cannot be performed, or that its performance cannot be claimed till the other has been performed, and the promisor of the promise last mentioned fails to perform it, such promisor cannot claim the performance of the reciprocal promise, and must make compensation to the other party to the contract for any loss which such other party may sustain by the non-performance of the contract. Illustrations (a) A hires B's ship to take in and convey, from Calcutta to the Mauritius, a cargo to be provided by A, B receiving a certain freight for its conveyance. A does not provide any cargo for the ship. A cannot claim the performance of B's promise, and must make compensation to B for the loss which B sustains by the non-performance of the contract. (b) A contracts with B to execute certain builder's work for a fixed price, B supplying the scaffolding and timber necessary for the work. B refuses to furnish any scaffolding or timber, and the work cannot be executed. A need not execute the work, and B is bound to make compensation to A for any loss caused to him by the non-performance of the contract. (c) A contracts with B to deliver to him, at a specified price, certain merchandise on board a ship which cannot arrive for a month, and B engages to pay for the merchandise within a week from the date of the contract. B does not pay within the week. A's promise to deliver need not be performed, and B must make compensation. (d) A promises B to sell him one hundred bales of merchandise, to be delivered next day, and B promises A to pay for them within a month. A does not deliver according to his promise. B's promise to pay need not be performed, and A must make compensation.