Indian requirements and regulations are somewhat hazy in regards to internships because there are many different perimeters encompassing an “internship”, such as length, type of compensation, and relationship to an educational institution or company. Therefore, depending on the length of stay and type of internship, the type of visa you need to apply for varies.
If your internship is less than six months, it is easiest to simply apply for a tourist visa. (Refer to the “You want to go on Reconnaissance” section for details.)
If your internship is longer than six months, is directly linked to a recognized educational institution in India and is not a paid position, you can apply for a student visa. A multiple entry visa will be granted for the duration of your academic internship, provided you can offer supporting documents from the Indian institution and proof of financial means. (See “You want to Study” for more details.)
If your internship is linked to an academic institution from outside of India (with no local affiliates) and is not a paid position (stipends are not considered a salaried position), you can apply for an entry (X) visa. Such a visa may be issued for a 6-month or 1-year period and is typically multiple entry, however, the validity period granted is often arbitrary. You may only be granted a six-month entry (X) visa (despite having a one-year internship contract) with the ability to apply for an extension from within India a month prior to its expiry.
An invitation from the Indian institution you will be interning with should be provided, along with proof of financial means. For example, the organization may offer lodging and/or a stipend to cover your daily living expenses. This does not count as salary (therefore fitting under the entry (X) visa application) so a letter from the organization that expresses that your living expenses are covered ensures that you do not require adequate funds to finance your stay in India.
If your internship is of a professional nature and you will be earning a salary, you will have to apply for an employment visa. (Refer to the “You have a Job and need to Relocate” section for details.) However, if it is at all possible to avoid this process for your internship, try to do so as it will greatly increase the processing time and bureaucracy involved.
In all of the above cases, dependents would need to apply for an entry (X) visa with your supporting documents.
Changing visa types is not permitted within India so you would have to return to your home country, if your internship leads to employment, to apply for an employment visa.