No, not necessarily. A polygraph is not required for a Top Secret security clearance, not even a TS/SCI. If you work for the FBI, CIA, NSA,DIA, or work in the Whitehouse, you will need what's called a Full Scope polygraph, or a polygraph that is a combination of two polygraphs usually administered separately. The CI poly is for actual counter intel - "Are you a spy?" type questions. The other test is called a Life Style poly, and up until 15 years ago, you could ask if someone was Gay, or engaged in 'deviant' behaviors. It's since changed to be more PC, but it's still unpleasant. Other things that can require a polygraph are certain defense contracts, where the customer stipulates that to have access to the data, you must pass either a CI, or a life style poly, or both. Outside of those situations, you are not required to have a poly to have a TS.