Dear Ksri_nivas
What you are referring to - i.e. "if union asked to deduct union fund to be deducted from employee salary in company payroll" - is a well-established Personnel (HR) practice in established big business houses, having recognized Unions.
In fact, this is also considered by Labour Deptt. as an authentic proof of the Membership of a particular Union when there is an issue relating to Recognized Union or Representative Union.
This practice is followed all over the Developed Industrial world. Here, the Unions request the Management for facilitating such deductions (union membership fees) from the salary of the employees.
An employee authorizes the management for such deductions by applying in a specified format.
This system is called the
"Check - Off" system.
This system is relatively unknown to HRs in IT/ITES sector or in small private companies; as they do not have (or do not allow) any employees Union or such practices are discouraged in their companies.
Here's a link to the website of National Insurance Co. wherein the Circular is displayed. Hope this helps you in understanding and implementing such a system in your company.
<link outdated-removed> ( Search On Cite | Search On Google )
Do revert back in case you have any further queries on this.
Warm regards.