The scheme allowed them to take a minimum of two years and a maximum of five years off the job with the airline.
"The airline has recently issued a circular to its employees on sabbatical, asking them to join back duty or put in their papers as they have completed the sabbatical period," Air India sources told PTI.
The salary bill of the airline is around Rs 3,000 crore per annum, accounting for around 20 per cent of the operational expenses of the debt-laden airline.
Employees have been given time till December end to inform the carrier of their choice, they added.
Around 213 employees mainly from the non-operational staff are currently availing the scheme, they said. The un-paid scheme was aimed at allowing staff to enhance skills.
The period for which the staff remained on sabbatical is considered as a lien which ensures that their jobs were protected if they wish to come back.
"While some of these secured jobs in others sectors, some moved to rival carriers. Some employees availed of the leave and settled down abroad," sources said.
A number of employees have retired over a period of time and with that the strength is reducing, they said, adding "so employees who join back will fill in those positions."
Of the total 27,000 employees of the airline, around 7,000 are expected to retire in the next three years and the carrier has not made any fresh recruitment other than those in the pilots and cabin crew category, that too based on the requirement, in the last couple of years.