Survey is a process meant to determine whether a factory / establishment is amenable to the provisions of the ESI Act 1948 for purpose of coverage.  There are two types of surveys:-
a) Surprise Survey
i) When a complaint is received from any employee or trade union any source etc about a factory that is coverable but not covered.
ii) When there is reasonable doubt that the provisions of  the Act are not made applicable to a factory deliberately.
b) Post Intimation Surveys
i) Such surveys are conducted when a list of factories is received from Chief Inspector of Factories EPFO(Employees Provident Fund Organisation)Industries deptt. Or the Labour Commissioner’s office etc.
ii) When a Municipal Corporation or a Nagar Parishad extends the geographical limit of municipalities in certain towns and cities.