Q.What is remission? How does it differ from waiver?

Both let a party off some or all of their obligation, but remission is specifically about accepting less than what was due, while waiver is a more general voluntary give-up of a right. …

Remission [Section 63] allows every promisee to (a) dispense with or remit, wholly or in part, the performance of the promise made to them, (b) extend the time for such performance, or (c) accept any satisfaction they think fit instead of performance — and no fresh consideration is needed for the promisee to do any of this. Example: B owes A ₹5,000; A agrees to accept ₹4,000 in full settlement of the debt — this is a valid remission, and A cannot later claim the remaining ₹1,000.

Waiver is a party who has a right under the contract voluntarily abandoning that right, releasing the other party from having to perform that part of the obligation. It is a broader idea than remission — remission specifically concerns accepting less/excusing a promise (often, though not only, of a monetary nature), while waiver more generally covers giving up any contractual right, whether or not it relates to a payment being reduced. …

Treating remission and waiver as identical terms — remission is the specific statutory mechanism (Section 63) for accepting less or excusing performance …