Learned Mr. Vasudevan and Mr. Meneon have given valuable advice. Kindly revert with details.
You must carefully read the communication sent to you regarding the change in notice period. Company might have written, company can reject notice pay in lieu of notice period, or employee can not tender notice pay in lieu of notice period etc...It shall be appropriate to show it to elders in the family, competent and experienced persons/well wishers, known to the family, lawyer/law firm before taking a final call on accepting the new terms.
Company reserves the right to formulate policies which suit it as per the ever changing business environment. Usually companies increase the notice period when they want to put a check on attrition and buy more time to find and train replacements, and they decrease the notice period when they have tested most of the employees and have decided to separate.
Employee must also update them on what suits them most and what can be detrimental to the interests. If you concur with one clause and do not with others you should clearly reject in writing and obtain proper acknowledgment. If you do not agree with the revised terms at all you can reject to accept. It is almost certain that you shall have to face sessions with your reporting authority/HR.
If you do not give your acceptance, the revised terms shall ideally be not applicable to you. You may post the details of your appointment letter.
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