Willing to serve Short notice period - but company will provide performance incentive if I server full 3 months

Dear sir, In my current employment notice period of 3 months. It is also written on my appointment letter. My Doj is 16-01-2018. I have resigned on 28-12-18 and willing to pay remaining days amount to company. I gave them 45 days notice of leaving. But they are rigid on to serve 3 months. And when i inquired for performance incentives they told me your last day is 28 march 19. And if it is 31march 19. They will provide incentive. Please guide me what should i do?
Thanks

Hi Dheerendra,
In the circumstances explained, you'll have mostly no option but to serve the full 3 months notice period. However if your terms & conditions of appointment provide for 'buying' of notice period i.e. the rest of the unserved NP of 45 days period, then you'll have chance of raising this option. And reg.'performance incentive' it's possible to get proportionate incentive for the period you served/becoming eligible for the same. That apart, how about joining the other employer with whom you are trying to join after this resignation by 28th March 2019. Talk them to gain extension of joining time to solve the issue.