Employees' State Insurance (General) Regulations, 1950
15. Allotment of insurance number
On receipt of the return required under regulation 14, the appropriate office shall promptly allot an insurance number to each a person in respect of whom the Declaration Form has been received unless it finds that the person had already been allotted an insurance number. The temporary identification certificate with insurance numbers marked thereon shall be detached and returned to the employer along with one copy of Form 3. The employer shall deliver the temporary identification certificate to the employee to whom it relates, after obtaining his signature or thumb-impression thereon except in the case of an employee to whom a certificate of employment has been issued under Regulation 17A. The Insurance Number allotted by the regional office to an employee and indicated in the copy of Form 3 returned to the employer, shall be entered by the employer on the contribution card of such employee.