Dear Khushi,
You wanted to take a declaration from the newly joined employee regarding his past employment. He is required to give a declaration because he is unable to provide the relieving letter.
However, the question that arises is why is he unable to provide the relieving letter? If not the relieving letter, have you done the reference check with his past company? Was he terminated because of misconduct? Will it be appropriate to just believe in the declaration given by the employee?
There is nothing wrong with obtaining a declaration from the employee. However, it is a last resort. It should be invoked provided the past company of the employee remains unresponsive to your reference check queries.
I am cautioning you because I have seen 1-2 cases wherein HR professionals believed in the declaration by the employee, but later, it emerged that the employee was involved in fraudulent activity. Hence the caution.
Thanks,
Dinesh Divekar