Hi

NEET eligibility criteria by nta  mentions nothing about appearing for improvement examination, but yes as per eligibility criteria by NTA for jee mains when one appears for improvement examination then he has to appear in all the five subjects otherwise it is not considered.

So, to be on the safer side to be eligible for your Neet examination if you are planning to give your 12th examination again  I would suggest you to give examination of all the 5 subjects- physics chemistry biology English and one more subject like Hindi Sanskrit Maths or any other subject of your choice  . You can even go for NIOS on demand examination for this 12th exam and don't worry NIOS is a recognised board and it is accepted for Neet examination.

Neet 2021 eligibility  criteria says that, to be eligible  one must be either appearing for the class 12th board examination 2021 or one must have passed 12th board examination with physics, chemistry ,biology/biotechnology and English and must have got at least  50  % in aggregate of PCB  i.e Physics, Chemistry and Biology/Biotechnology  in 12th examination  if belongs to general category , or   at least  40%  in aggregate of PCB if belongs to  Obc/ Sc /st category  , or at least 45 % in aggregate of PCB in case of general pwd candidates to be eligible.

So, after passing if you fulfill this percentage requirement in PCB as per your category then you will be eligible for Neet examination and after qualifying Neet examination you can get admission in MBBS BDS Ayush courses like BAMS, BHMS, veterinary i. e BVSc on the basis of marks/ rank obtained by you in NEET examination.

Also,
to be eligible for neet 2021 one has to be at least 17 years old or more by  31st  December 2021

For detailed information about neet examination eligibility go through our page for which link is provided below; -

https://medicine.careers360.com/articles/neet-eligibility-criteria

Thank you