Unilateral post-execution contract variation rejected where GST terms in the work contract had already been concluded and acted upon.

After execution and completion of the work, a later communication seeking to withdraw the earlier GST-related stipulation and alter the letter of acceptance was an impermissible unilateral variation of a concluded contract. The court held that the substituted Clause-9 governing GST treatment had already been acted upon, so the respondents could not retrospectively adjust payments on the basis of the 06.09.2021 communication. That communication and all actions taken under it were set aside as illegal, and the parties were directed to proceed in accordance with the earlier contractual position.

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Issues: Whether the respondents could, after execution of the work, withdraw the earlier GST-related stipulation and alter the terms of the letter of acceptance by the communication dated 06.09.2021.

Analysis: The terms governing the work contract, including the GST treatment reflected in the substituted Clause-9, had already been acted upon and the work stood completed. A later communication purporting to withdraw that stipulation and adjust payments was an attempted post-execution variation of the contractual terms. Such unilateral alteration of an concluded contractual arrangement was held to be unsustainable.

Conclusion: The impugned communication dated 06.09.2021 was set aside, and all actions taken on its basis were declared illegal.

Final Conclusion: The writ petition succeeded, and the respondents were directed to proceed in accordance with the earlier contractual position.

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