You should be 17 years as on December 31st of the year of admission for NEET. For example, if you are in Class 11 right now and you will be in Class 12 next year, you will be appearing for NEET in 2021. To be eligible for NEET 2021, you should be 17 years atleast by December 31st of 2021. If this is the case, then you can appear for NEET 2021. But if you will not be 17 years by December 31st of 2021, then you have to consider appearing for NEET 2022. Now we understand that 1 year is a long wait. Many Candidates take up various other courses and then simultaneously prepare for NEET. You can do that as well. But if you want to focus on NEET alone, you may have to consider taking a break for 1 year and only concentrate on NEET preparation. To help you with your NEET preparation, we have NEET Knockout packages that you can check at: https://learn.careers360.com/knockout-neet-may/.