How often are members of the Indian parliament elected?

Duration of Rajya Sabha

• It is a permanent body and not subject to dissolution.
• One-third of members of the Rajya Sabha retire every second year. 
• Their seats are filled up by fresh elections and presidential nominations at the beginning of every third year.
• The retiring members are eligible for re-election and renomination any number of times.
• The Constitution has not fixed the term of office of members of the Rajya Sabha and left it to the Parliament.
• Accordingly, the Parliament in the Representation of People Act (1951) provided that the term of office of the members of the Rajya Sabha shall be six years. 

Duration of Lok Sabha

• The Lok Sabha is not a continuing chamber. 
• Its normal term is five years from the date of its first meeting.  

Further Reading:

• Lok Sabha 
• Rajya Sabha
• List of Cabinet Ministers of India, 2021

To read more about the Functions of the Parliament, check the linked article.