Answer: When it tries to influence the government for it's own benefit.
Step-by-step explanation:
When people who have the same views on a certain public policy come together and try to influence the government in order for the government to enact policy that favors the views of that group, that group is called an Interest group.
An organization therefore becomes an interest group when it tries to influence the government. A very popular example of an interest group is the National Rifle Association (NRA) which lobbies the government to protect gun rights.