"Wrapping up new book in female first person. Can't wait to share details with all of you. Releases this Diwali," Bhagat said in a tweet.
The 42-year-old author has been active on twitter posting developments from the sets of the upcoming film 'Half Girlfriend', based on his book of the same name.
The Mohit-Suri directed underproduction film stars Arjun Kapoor and Shraddha Kapoor and is scheduled for release next year.
Bhagat's novels 'Five Point Someone', 'One Night @ the Call Center', 'The 3 Mistakes of My Life' and '2 States: The Story of My Marriage' have all been previously adapted for Bollywood.