Different Labour enactment has different applicability provisions depending upon the number of employees employed. Therefore, if you have just a single employee also certain Act, like, Minimum Wages Act will be applicable to you and you may run without coverage of a particular provision of an Act till your number of employees reach 100, say Chapter VB of the Industrial Disputes Act and as on. On the other hand, the applicability of Payment of Bonus Act depends on number of employees as well as the year in which the establishment makes profits upto a certain period, say five years. That means, different Acts have different coverage parameters.
Just to brief you, I append the following:
Once you employ one person:
Minimum Wages Act
Payment of Wages Act
Equal Remuneration Act
Employees Compensation Act,
Industrial Disputes Act
Once your number of employees becomes 10:
Maternity Benefits Act
ESI Act
Payment of Gratuity Act
Setting up of Internal Committee for Prevention of Sexual Harassment at Workplace
Once your number of employees becomes 20:
EPF &MP Act
Payment of Bonus Act subject to the provision of infancy protection (5 years)
Constitution of Grievance Redressal Committee under ID Act
Once your number of employees becomes 50:
Standing Order Act
Provisions of Lay off, Notice of retrenchment, closure etc of ID Act
Once your number of employees becomes 100:
Chapter VB of ID Act will become applicable
CLRA Act when your total number of employees engaged through contractor(s) becomes 20
Interstate Migrant Workers (Regulation of Employment and Conditions of Service) Act when the number of migrant workers engaged through a contractor becomes 5