Hi there! Thanks for reaching out to us at Careers360 about NIOS additional subjects.

So, if your first admission validity is complete, you'll need to go through a fresh registration process for the additional subject. Here's the general process:

1. Register for the additional subject on the NIOS website

2. Pay the required fee

3. Choose your exam mode - public exam or on-demand exam

For additional subjects, you can choose either the public exam or on-demand exam. The public exam happens twice a year (April-May and October-November), while on-demand exams offer more flexibility in timing.

If you need to complete the subject quickly, the on-demand exam might be a good choice. But if you prefer the regular exam schedule, go for the public exam.

Is there a specific subject you're looking to add? Let me know if you need any more info!