What are the eligible criteria and procedure to apply for SSC private exam in Karnataka

They can register as Private candidate from NIOS(National Institute of Open Schooling). The National Institute of Open Schooling was set up as the National Open School in the year 1989. It is an open schooling system and about 2.81 million candidates in past 5 years qualified through this. Since 1991.
They can go to regional NIOS office in Bangalore. They have to submit an application and they should attach copies of the following documents
1)Transfer Certificate from his previous School
2)Bonafide certificate
The NIOS will register them as private candidates. So, they can appear for the next upcoming 10th class exams without studying in any school.

For those students who do not have an opportunity to give class 10 exam in the regular stream the Govt of India has made one institution named as National Institute of Open Schooling (NIOS) which is the board of education under the Union Government of India. So student of Karnataka also can go for class 10 through this by registering in it online. One has to register and pay the fees and then ca appear in the exam on the stipulated days. The official site of this board is - www.nios.ac.in

Another possibility is if Karnataka state board is also entertaining for private candidates then one can fill the private form when the regular students are filling it for their exam and then get the schedule of exam from the board and appear in it. One has to find out it from the respective state board. So, today there are some avenues to apply in private SSC exam and one can try through those.

National Institute of Open Schooling was initiated way back to 1989 with a view to promoting studies of the students belonging to deprived categories in terms of financial status.
What is needed at this juncture is to approach the Regional - office of Bangalore with the School leaving Certificate of the school from where one has received his earlier education.
Bonafide - certificate is also required to be produced before the Regional - office.
Upon submission of the photocopies of such documents, one will be registered as a private candidate eligible to appear for class ten examination.
Alternatively, Registration can also be done through the Karnataka Board. One has to write an application to the secretary of the Board along with a demand draft of a requisite amount and a forwarding note written by the Principal of the school you attended last.
You may proceed either of the routs.